This PR contributes to#1508 by fully annotating the following modules to supportmypy --strict compatibility:

✅ Files Updated

• google/auth/transport/__init__.py – fully typed abstract base classes forRequest andResponse
• google/auth/transport/requests.py – concrete implementation with strict typing

📌 Highlights

• All functions and methods include explicit return type annotations
• Deprecated@abc.abstractproperty replaced with@property + @abc.abstractmethod
• __call__() inRequest interface now explicitly typed
• All mypy strict errors resolved, including:
  • Line 53: missing return onstatus
  • Line 58: missing return onheaders
  • Line 63: missing return on__call__
  • Line 78: untyped helper function

✅ Verified

mypy --strict google/auth/transport/__init__.pymypy --strict google/auth/transport/requests.py