CI

[Luke100000]

Adds an example project and a matrix compatibility test over all supported versions and platforms via GitHub actions. This should cover newly introduced issues and also help discover some existing issues.

• The most recent AppImage fix seems to be not backwards compatible
• The appimages from "11.3", "0.10.2", "0.9.2" may contain an outdated version of libmpg123 (I excluded them for now from tests). I can "fix" that by removing this lib form the appimage manually and use the system one.
• Some ancient love builds had different layout, and additional files causing makelove to fail

Right now GitHub has service degradations and /latest in the releases does not work. I will change that back once resolved.

MR depends on uv changed from #53