Enfoce reuse compliance

[hexagonrecursion]

The https://reuse.software specification is the standard for providing machine-readable licensing and copyright information.

I believe:

• machine-readable metadata is a good thing.
• licensing and copyright matter
• automation is a good thing.

Therefore I propose we:

1. Make this repository compliant with the https://reuse.software/ specification
2. Enfoce compliance via a github action