add result_processor to handle UUID conversion; enhance tests for UUI…

[h0rn3t]

This pull request improves the handling of UUID values in the psqlpy_sqlalchemy dialect to ensure that UUID columns are returned as uuid.UUID objects instead of strings. It also adds regression tests to verify this behavior and prevent future issues.

UUID handling improvements:

• Added a result_processor method to the custom UUID type in psqlpy_sqlalchemy/dialect.py to convert string or bytes UUID values returned by psqlpy into Python uuid.UUID objects when as_uuid=True. This ensures compatibility with SQLAlchemy 2.0+ and correct type handling for UUID columns.

Testing and regression coverage:

• Added two regression tests in tests/test_uuid_support.py:
  • test_uuid_select_returns_uuid_objects verifies that selecting a UUID column returns a uuid.UUID object, not a string.
  • test_uuid_select_full_row ensures that selecting a full row returns the UUID field as a uuid.UUID object.…D return types