Ensure `pre-commit` linting is run in CI

[sirosen]

In #38 , I noted that we don't have pre-commit linting running in CI.
I think I configured this via pre-commit.ci in the past, but maybe that broke with the repo move.

I intend to setup pre-commit.ci again, since it gives the nice autofixing commits.
I've seen some projects setup both that and a GitHub Actions job for this, but I don't quite understand the goals of that configuration. So I don't intend to do that.

[henryiii]

The reason to do both is primarily for something with slow CI, you can use "needs" if it's in GitHub Actions to keep the slow CI from starting if it's not passing the pre-commit check. For anything small, no, not really a reason to do both.