Compress release tarballs with XZ

[pacho2]

Current release tarballs are compressed using gzip, with it, for example for latest version, the file size is 976M. On the other hand, if compressing with XZ, it can be as small as 262M.

That could help lots of bandwidth and space

Thanks a lot

[simoncozens]

Thank you, that's a good idea, at least for the monthly releases. Currently I'm being lazy and using create-release to make the release artefacts, which limits things to how GitHub does it (zip and tarball). I'd need to change to something like softprops/action-gh-release and create the release .tar.xz as part of the action, which is a bit more complicated but I agree it's worthwhile.