add license information to setup.cfg

[HeinrichAD]

This PR adds the MIT license information from the LICENSE.md file into the setup.cfg.

Intension

It would be great if this package would provide its MIT license information to pip and therefore supports commands like: pip show ansi or also packages like pip-licenses.

Compare before and after

  $ pip show ansi
  Name: ansi
  Version: 0.3.6
  Summary: ANSI cursor movement and graphics
  Home-page: https://github.com/tehmaze/ansi/
  Author: Wijnand Modderman-Lenstra
  Author-email: maze@pyth0n.org
- License:
+ License: MIT License
  Location: /home/<user>/.local/lib/python3.10/site-packages
  Requires:
  Required-by: