Run tests on gh actions

[idbrii]

Related #60.

Can't figure out what's wrong with travis, but gh actions seem to work. Migrated travis.yml to runtest.yml and removed travis.yml.

coveralls fails for me because I don't have the account there, but it's reporting coverage amounts before it fails to upload.

Tests against multiple versions of lua using leafo's matrix.luaversion with roughly the same versions as travis.yml.

You can see example results here: https://github.com/idbrii/love-cpml/runs/2900023706

What's missing

Notification setup from travis is missing. Github sends email notifications. You can choose:

• Email
• Web
• Send notifications for failed workflows only There are third-party irc gh actions, but I don't see how you'd do on_success: change in an action.

luacheck was disabled in travis.yml, so it's disabled here too.

[idbrii]

luacov-coveralls is failing when even run from here and explicitly given the repo token. Not sure I can debug that, so I've set it to allow failure. Maybe the token needs to be refreshed?

Aside from that, it works!