Alpine github workflow

[henderkes]

see title, we should have one, the docker containers depend on it

[crazywhalecc]

It sounds like we can just switch our current tests.yml to bin/spc-alpine-docker?

[henderkes]

I'm not too familiar with github workflows. spc-alpine-docker as an additional (!) test would suffice in my eyes.

[crazywhalecc]

Finished in #685