Include license file in the generated wheel package

[jdufresne]

The wheel package format supports including the license file. This is done using the [metadata] section in the setup.cfg file. For additional information on this feature, see:

https://wheel.readthedocs.io/en/stable/index.html#including-the-license-in-the-generated-wheel-file

Helps project comply with its own license:

4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions:

   (a) You must give any other recipients of the Work or Derivative Works a copy of this License;

[theacodes]

Thanks, @jdufresne!