Improve type hints for fastapi example

[waketzheng]

Fix mypy complaint for class that is dynamic created by pydantic_model_creator

Description

1. After remove the module = ["examples.*"] section in pyproject.toml and then run mypy main.py in examples/fastapi/, it raises:

   main.py:36: error: Variable "models.User_Pydantic" is not valid as a type  [valid-type]
   main.py:36: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#variables-vs-type-aliases
   main.py:42: error: Variable "models.UserIn_Pydantic" is not valid as a type  [valid-type]
   main.py:42: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#variables-vs-type-aliases
   main.py:43: error: UserIn_Pydantic? has no attribute "model_dump"  [attr-defined]
   main.py:53: error: Variable "models.UserIn_Pydantic" is not valid as a type  [valid-type]
   main.py:53: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#variables-vs-type-aliases
   main.py:54: error: UserIn_Pydantic? has no attribute "model_dump"  [attr-defined]
   Found 5 errors in 1 file (checked 1 source file)

2. cd examples/fastapi && pytest _tests.py show warning message with newer version of httpx:

   site-packages/httpx/_client.py:1426: DeprecationWarning: The 'app' shortcut is now deprecated. Use the explicit style 'transport=ASGITransport(app=...)' instead.
   warnings.warn(message, DeprecationWarning)

Motivation and Context

Our team have some projects tha using fastapi+tortoise-orm+mypy. It cost me a lot of time to find a pythonic way to fix mypy complaint about Xxx_Pydantic, finally this comment https://github.com/pydantic/pydantic/issues/615#issuecomment-504618897 give me the answer.

How Has This Been Tested?

make ci

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added the changelog accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[coveralls]

Pull Request Test Coverage Report for Build 9030535545

Details

• 6 of 6 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 87.935%

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Totals
Change from base Build 9028420328:	0.003%
Covered Lines:	5772
Relevant Lines:	6468

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💛 - Coveralls