Cryptography now requires Rust. Use the newer pip to install the
pre-built wheel.

Based on what's in Debian testing.

The templates were changed and this reflects the changes:
- No need to set the order of the stages, pre-commit runs  in .pre now.
- Rename the Docker jobs for clarity and avoiding more common names.

- Update hooks.
- Add hook to validate .gitlab-ci.yml.

Because there are now scheduled CI runs.

Replace cgit with GitLab.