text: Title: TypeError: 'default' is an invalid keyword argument for this function
  Body: 请教例子就报错是咋回事？
  
  
  INFO:     Started server process [28391]
  INFO:     Waiting for application startup.
  INFO:     Application startup complete.
  INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
  
  
  Error: 'default' is an invalid keyword argument for this function
  Traceback: Traceback (most recent call last):
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/errors.py", line 162, in __call__
      await self.app(scope, receive, _send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 79, in __call__
      raise exc
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 68, in __call__
      await self.app(scope, receive, sender)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
      raise e
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
      await self.app(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/routing.py", line 718, in __call__
      await route.handle(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/routing.py", line 276, in handle
      await self.app(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/routing.py", line 66, in app
      response = await func(request)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/routing.py", line 237, in app
      raw_response = await run_endpoint_function(
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/routing.py", line 163, in run_endpoint_function
      return await dependant.call(**values)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi_amis_admin/admin/admin.py", line 477, in route
      return await self.page_parser(request, page)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi_amis_admin/admin/admin.py", line 435, in page_parser
      result = page.amis_html(
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi_amis_admin/amis/components.py", line 131, in amis_html
      "AmisSchemaJson": self.amis_json(),
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi_amis_admin/amis/types.py", line 23, in amis_json
      return self.json(exclude_none=True, by_alias=True)
    File "pydantic/main.py", line 504, in pydantic.main.BaseModel.json
  TypeError: 'default' is an invalid keyword argument for this function
  
  INFO:     127.0.0.1:58286 - "GET /admin/ HTTP/1.1" 500 Internal Server Error
  ERROR:    Exception in ASGI application
  Traceback (most recent call last):
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/uvicorn/protocols/http/httptools_impl.py", line 398, in run_asgi
      result = await app(self.scope, self.receive, self.send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/uvicorn/middleware/proxy_headers.py", line 45, in __call__
      return await self.app(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/uvicorn/middleware/debug.py", line 81, in __call__
      raise exc from None
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/uvicorn/middleware/debug.py", line 78, in __call__
      await self.app(scope, receive, inner_send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/applications.py", line 276, in __call__
      await super().__call__(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/applications.py", line 122, in __call__
      await self.middleware_stack(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/errors.py", line 184, in __call__
      raise exc
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/errors.py", line 162, in __call__
      await self.app(scope, receive, _send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/base.py", line 109, in __call__
      await response(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/responses.py", line 277, in __call__
      await wrap(partial(self.listen_for_disconnect, receive))
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/anyio/_backends/_asyncio.py", line 662, in __aexit__
      raise exceptions[0]
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/responses.py", line 273, in wrap
      await func()
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/base.py", line 134, in stream_response
      return await super().stream_response(send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/responses.py", line 262, in stream_response
      async for chunk in self.body_iterator:
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/base.py", line 98, in body_stream
      raise app_exc
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/base.py", line 70, in coro
      await self.app(scope, receive_or_disconnect, send_no_error)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 79, in __call__
      raise exc
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 68, in __call__
      await self.app(scope, receive, sender)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
      raise e
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
      await self.app(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/routing.py", line 718, in __call__
      await route.handle(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/routing.py", line 443, in handle
      await self.app(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/applications.py", line 276, in __call__
      await super().__call__(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/applications.py", line 122, in __call__
      await self.middleware_stack(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/errors.py", line 184, in __call__
      raise exc
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/errors.py", line 162, in __call__
      await self.app(scope, receive, _send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 79, in __call__
      raise exc
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 68, in __call__
      await self.app(scope, receive, sender)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
      raise e
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
      await self.app(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/routing.py", line 718, in __call__
      await route.handle(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/routing.py", line 276, in handle
      await self.app(scope, receive, send)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/starlette/routing.py", line 66, in app
      response = await func(request)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/routing.py", line 237, in app
      raw_response = await run_endpoint_function(
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi/routing.py", line 163, in run_endpoint_function
      return await dependant.call(**values)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi_amis_admin/admin/admin.py", line 477, in route
      return await self.page_parser(request, page)
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi_amis_admin/admin/admin.py", line 435, in page_parser
      result = page.amis_html(
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi_amis_admin/amis/components.py", line 131, in amis_html
      "AmisSchemaJson": self.amis_json(),
    File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/fastapi_amis_admin/amis/types.py", line 23, in amis_json
      return self.json(exclude_none=True, by_alias=True)
    File "pydantic/main.py", line 504, in pydantic.main.BaseModel.json
  TypeError: 'default' is an invalid keyword argument for this function
  