fix: remove setup.cfg configuration for creating universal wheels

[parthea]

The file setup.cfg contains a setting to create a Universal Wheel which is only needed if libraries support both Python 2 and Python 3. Python Cloud Client Libraries only support Python 3 so this setting is no longer needed. See https://packaging.python.org/en/latest/guides/distributing-packages-using-setuptools/#wheels.

This will resolve the following warning in this build log from PR #13644:

Building wheels for collected packages: googleapis-common-protos
  Building wheel for googleapis-common-protos (pyproject.toml): started
  Building wheel for googleapis-common-protos (pyproject.toml): finished with status 'error'
  error: subprocess-exited-with-error
  
  × Building wheel for googleapis-common-protos (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> [40349 lines of output]
      running bdist_wheel
      /tmp/pip-build-env-9o_3w17v/overlay/lib/python3.13/site-packages/setuptools/_distutils/cmd.py:135: SetuptoolsDeprecationWarning: bdist_wheel.universal is deprecated
      !!
      
              ********************************************************************************
              With Python 2.7 end-of-life, support for building universal wheels
              (i.e., wheels that support both Python 2 and Python 3)
              is being obviated.
              Please discontinue using this option, or if you still need it,
              file an issue with pypa/setuptools describing your use case.
      
              By 2025-Aug-30, you need to update your project and remove deprecated calls
              or your builds will no longer be supported.
              ********************************************************************************
      
      !!