1.0.22: Downgraded Ubuntu VS version for Windows the build

For whatever reason compiling Windows native binaries on Ubuntu 22.04 produces a 32-bit binary that doesn't work (the 64-bit one does work).
Compiling them on Ubuntu 20.04 produces working binaries, which are also both much smaller than the ones from Ubuntu 22.04.

1.0.21

Added workflow run for PRs as a CI check

20160124

Cache metamethods in each LuaRuntime. #2

20151127

Cache metamethods, finalize references #1

20140425

Including some fixes for OpenRA/OpenRA#5190