Fix CI

This repository's main branch currently does not pass all CI checks. This makes detecting issues in PRs harder and might result in a broken track, and so is an important thing to fix.

The following CI workflows are currently failing:

https://github.com/exercism/swift/runs/3370849643

Tracking

https://github.com/exercism/v3-launch/issues/55

The CI job is fixed by #487 and the Configlet job is fixed by #484.

I don't know what the CircleCI job is still doing, since there is no .circleci/config.yml in the repo (anymore). Perhaps this integration is outdated after #398 and can be disabled?

@ErikSchierboom Tests pass here