chore(models): add type hints to improve type safety

[deyjoy]

Summary

This pull request adds type hints to the models.py file in the requests library. The goal is to improve code readability and maintainability by specifying the expected types for function arguments and return values.

Changes

• Added type hints to all functions and methods in models.py.

Checklist

• Add type hints to function signatures.
• Run tests to verify no breaking changes.

Testing

All existing tests were run to ensure that adding type hints did not introduce any breaking changes. The test results are as follows:

• 602 tests passed
• 3 tests skipped
• 1 test expected to fail (xfail)
• 18 warnings

Warnings

The following warnings were noted during testing:

• DeprecationWarning: Non-string usernames will no longer be supported in Requests 3.0.0.
• DeprecationWarning: Non-string passwords will no longer be supported in Requests 3.0.0.
• DeprecationWarning: In requests 3.0, get_encodings_from_content will be removed.
• InsecureRequestWarning: Unverified HTTPS request is being made to host 'localhost'. Adding certificate verification is strongly advised.

These warnings do not impact the functionality of this PR but should be addressed in future updates.

[nateprewitt]

Thanks for the PR, @deyjoy. Typing for Requests is already available in typeshed as stubs. We likely won't be adding inline typing to Requests in the near future.

[deyjoy]

Thank you for the update, @nateprewitt. I understand that inline typing won't be added as typings are already available in typeshed stubs. I appreciate the feedback and the chance to contribute. I will look for other areas where I can assist. If there are any specific needs or suggestions, please let me know. Thanks again for the opportunity!