[CI] What about migrating to GitHub actions?

[erikmd]

as mentioned in #356 (comment), some recent issues w.r.t. the PR status feedback from Travis → GitHub, and the stability of the macOS build on Travis CI make me wonder whether it'd be useful to switch learn-ocaml's CI to GitHub Actions.

@yurug do you have an opinion on that?

AFAICT, the features provided by GitHub Actions are quite nice, and maybe the current test scripts could probably be reused with very few changes(?) − If need be I could have a look to prepare a PR, but not this week unfortunately :-/

[yurug]

That is something I was actually thinking about too. If you think you can prepare a PR to that end, that would be great!

[erikmd]

OK @yurug, thanks for your reply! I'll prepare a PR then

[erikmd]

@yurug the configuration I prepared is almost ready; I'll open the PR on this Wednesday.