Add CI

[LilithHafner]

Runs tests and builds documentation.
Fixes #7
CI should fail due to #8 (we'll see)

[tecosaur]

Much appreciated! (aside: it's a pity you can just reference another workflow and say "run that here" in a few lines)

[tecosaur]

Ah, failures in <1.11 are (currently) expected, since they don't have the new Base string type. We probably want to adjust the CI for that.

[LilithHafner]

it's a pity you can just reference another workflow and say "run that here" in a few lines

There's the github actions marketplace which comes close, but it doesn't meet the "in a few lines" criterion.