Unit tests + CI with GitHub Actions

[Luis-Varona]

As I discussed briefly with @nathanieljohnston in person yesterday—with the recent release of v1.0, now seems as appropriate a time as any to start adding unit tests to QETLAB in a test/ folder. (See this article on class-based unit tests in MATLAB.)

It would also be prudent to implement continuous integration via GitHub Actions to run these tests every time a commit/pull request happens in master to make sure new additions don't contain bugs. For instance, we had trouble recently with a bug in IskIncoherent.m that went unnoticed for a whole year (from #29 to #35). At the same time, we could use the same CI pipeline to set up automated documentation with GitHub Pages as suggested by @cosenal in #9 a veryyy long time ago, hehe.

I volunteer to get started on this issue come late August-ish (at a rather leisurely pace—I'm a busy cat!). Meow! 🐈 🐈‍⬛ 🐢 🐿️ 🐁

UPDATE: I've just realized we already have a website for documentation , but the fact remains that it's not automated. I'll look into whether it's possible to update a Wikimedia site automatically with GitHub Actions.