I'll decide on this later.

I can leave the automated builds in Docker Hub, but this way the images
will be identical and the hashes will match.

- Bandit complains on using urlopen, ignore since I'm using a hard-coded
URL.
- Pylint complains on the module name, rename.
- Remove the docker-compose hook, no docker-compose.yml.

Run pre-commit, build and push. Add badge.

- Newer Python.
- Newer Alpine.

More hooks (form the snippets in GitLab) and newer ones.