Drop fastapi-utils.InferringRouter in favor of fastapi.APIRouter

[jdavcs]

As per fastapi-utils: "InferringRouter is deprecated, as its functionality is now provided in fastapi.APIRouter", DeprecationWarning (ref https://github.com/dmontagu/fastapi-utils/blob/master/fastapi_utils/inferring_router.py).

I think fastapi.APIRouter is all we need.

Note: this is also part of solving the issue of fastapi-utils requiring SQLAlchemy < 2, which prevents us from upgrading to SA 2.0.

How to test the changes?

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• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.