Github CI builds

[Mehgugs]

Mentioned in #1:

Perhaps it would be simpler to provide tarballs that already contain the generated luacore.h? Is there an easy/automated way to do that on Github?

You can have github build the repo and then create releases using the artefacts or simply link to them, the only downside being you have to program github actions in yml.
You can have a matrix of different environments if you want to make builds for lua's other makefile platforms.

Github actions are a can of worms, so consider this a "proof of concept" rather than a feature request😅