text: Title: Typing error in generated client when response attribute use reserved keywords
  Body: **Describe the bug**
  I am using this library to generate a Python client for Jira using [their OpenAPI spec](https://developer.atlassian.com/cloud/jira/platform/swagger-v3.v3.json).
  
  I get a strange bug at import time:
  ```
    File "D:\Repos\jira_generated\the-jira-cloud-platform-rest-api-client\the_jira_cloud_platform_rest_api_client\models\json_node.py", line 38, in JsonNode
      int_value: Union[Unset, int] = UNSET
    File "C:\Apps\Python38\lib\typing.py", line 261, in inner
      return func(*args, **kwds)
    File "C:\Apps\Python38\lib\typing.py", line 358, in __getitem__
      parameters = tuple(_type_check(p, msg) for p in parameters)
    File "C:\Apps\Python38\lib\typing.py", line 358, in <genexpr>
      parameters = tuple(_type_check(p, msg) for p in parameters)
    File "C:\Apps\Python38\lib\typing.py", line 149, in _type_check
      raise TypeError(f"{msg} Got {arg!r:.100}.")
  TypeError: Union[arg, ...]: each arg must be a type. Got <the_jira_cloud_platform_rest_api_client.types.Unset object at 0x0000018CF4EEA070>.
  ```
  
  After investigating for a while, I came to the conclusion that it's because the `JsonNode` object has an attribute named "int". The attribute shadows the built-in name `int` and causes type hinting to fail:
  
  ```python
  @attr.s(auto_attribs=True)
  class JsonNode:
      """  """
  
      ... # Other attributes
      int: Union[Unset, bool] = UNSET
      ... # Other attributes
      int_value: Union[Unset, int] = UNSET  # Breaks here!
      ... # Other attributes
  ```
  
  **To Reproduce**
  Steps to reproduce the behavior:
  1. Generate the client for Jira: openapi-python-client generate --url https://developer.atlassian.com/cloud/jira/platform/swagger-v3.v3.json
  2. cd to the generated directory and open a Python shell
  3. Import `get_changelogs`: `from the_jira_cloud_platform_rest_api_client.api.issues import get_change_logs` or anything else indirectly using `JsonNode`
  
  **Expected behavior**
  A different name may need to be used here like `int_` or similar.
  
  **OpenAPI Spec File**
  https://developer.atlassian.com/cloud/jira/platform/swagger-v3.v3.json
  
  **Desktop (please complete the following information):**
   - OS: Windows 10
   - Python Version: 3.8.8
   - openapi-python-client version: 0.8.0
  
  **Additional context**
  Thanks for the great tool!
  