CI: Switch away from TravisCI about slop

[leejarvis]

I'm not against this but could you add some description of why we want to move to Circle (or move away from Travis, whichever is the motivator)?

[rickhull]

I don't have time right now to make a PR, but here is how I did it recently:

rickhull/compsci@93ff361

Briefly:

The on key tells GHA which files should trigger a CI run. so lib test .github and Rakefile

The jobs key tells GHA about the CI (test) job. Run on Ubuntu; don't fail fast (keep trying other rubies in the testing matrix); etc

[rickhull]

Travis got bought by private equity and they reneged on their lifetime support of open source. Service levels are way down with big delays, and there is a very limited number of "credits" for open source repos. When you run out, you can beg for more via email.

GH Action is a little more verbose but more powerful in job definition. Also seems to run much faster than Travis ever did.

[leejarvis]

Thanks, @rickhull -- in that case I support this change! If nobody gets to it before me I'll try to take a look soon.

[leejarvis]

I sort-of got this working with a new CI workflow (based on @rickhull's project). One thing that doesn't seem to work as I expected though is when a PR has been "fixed" (i.e. is now passing CI), the workflow details disappear entirely, and the "checks" tab seems to show "Waiting for checks information..." indefinitely.

Still, this is better than nothing so I'll leave it as-is for now and revisit once we've processed some PRs.

[olleolleolle]

🕺