Note that a spindle instance has to be chosen before pipelines are run in the repo settings. This doesn't port over the testing across multiple node versions that github had. The easiest way to do that as far as I can see would be having two workflows, each pulling in a separate `nodejs<ver>` package from nixpkgs. Maybe I'm missing something in the docs (https://docs.tangled.org/spindles.html#pipelines), though? For now, I think it's fine to test on a single version of node anyway.