There's no need to run it in a specific runner, but I did because I
set tags on the runners but didn't set them to run untagged (fixed in
gitlab-runner-docker@dfc42dda).

Setup pre-commit and add it to CI. Correct a few things as well.

Pull a new image and build without caching. I want updates for existing
packages without changing files.

- Image with Debian, Python and Golang packages installed.
- Deployment with Docker Compose and GitLab CI.