text: Title: 无法创建管理员账户
  Body: 参考了 #75，但依然无法新建。是否可以提供详细的例子？以下是代码
  
  ```python
  # main.py
  from fastapi import FastAPI, Request
  from adminsite import site, async_database
  from sqlmodel import SQLModel
  from starlette.middleware.base import BaseHTTPMiddleware
  
  
  app = FastAPI()
  auth = site.auth
  auth.backend.attach_middleware(app)
  app.add_middleware(BaseHTTPMiddleware, dispatch=async_database.asgi_dispatch)
  
  # 挂载后台管理系统
  site.mount_app(app)
  
  @app.on_event("startup")
  async def startup():
      await site.db.async_run_sync(SQLModel.metadata.create_all, is_session=False)
      # Create default admin user,user name:admin,password:admin,please change it after login!!!
      await auth.create_role_user('admin')
  
  
  if __name__ == '__main__':
      import uvicorn
  
      uvicorn.run(app)
  ```
  
  ```python
  # adminsite.py
  from fastapi_user_auth.auth.backends.jwt import JwtTokenStore
  from sqlalchemy.ext.asyncio import create_async_engine
  from sqlalchemy_database import AsyncDatabase
  from fastapi_user_auth.site import AuthAdminSite
  from fastapi_user_auth.auth import Auth
  from fastapi_amis_admin.admin.settings import Settings
  
  
  async_db_url = (
      "mysql+asyncmy://root:password@127.0.0.1:3306/admin"
  )
  engine = create_async_engine(
      async_db_url,
      pool_size=10,
      max_overflow=20,
      pool_pre_ping=True,
      pool_recycle=3600,
      pool_reset_on_return="rollback",
      echo=False,
      echo_pool=True,
      future=True,
      connect_args={"charset": "utf8mb4"},
  )
  
  async_database = AsyncDatabase(engine)
  
  auth = Auth(
      db=async_database,
      token_store=JwtTokenStore(secret_key='06c17af47a244bfee96020e9de676d75a5b5fbe1994e342c0b4c03a14e5c197142bc0bcadc2f5f182fdb88e269b40ba3660d004f9d7673a7d9da86a4052b7b29')
  )
  
  site = AuthAdminSite(
      settings=Settings(
          site_title="后台管理系统",
          language="zh_CN"
      ),
      auth=auth,
      engine=engine,
  )
  