Including a license file

[jakirkham]

It would be good to include a license file in the project. This is needed for other people that would like to use the project. It also is often required when creating packages for users to install.

Additionally it would be good to add a MANIFEST.in, which includes the license file and add a setup.cfg that also includes a license file. This ensures that other package types produce include and ship the license file for easier downstream consumption.

[jakirkham]

cc @hanslovsky (for awareness)

[cmalinmayor]

Looks like there is now an MIT license file and it is included in the pyproject.toml.