Allow CI jobs to run in parallel

Currently in the `ci.yml` workflow the jobs are configured so that `core` doesn't run until after `pre-commit`, and most of the other jobs don't run until after `core`. Removing those dependencies would speed up execution by allowing the jobs to run in parallel. Also, because of that configuration the later jobs only run if the earlier jobs are successful. I've run into issues with this when I've pushed a PR where the `pre-commit` job failed, and then after fixing that I found that the later jobs were failing for a different reason.