.gitlab-ci.yml: Use bookworm instead of python3-devel image
Use the docker-registry.wikimedia.org/bookworm image for the lint
job instead of docker-registry.wikimedia.org/python3-devel which
currently suffers from the bullseye-backports apt problem. This
change can be reverted (and the tag on the
docker-registry.wikimedia.org/python3-devel image can be updated)
when the image is updated.
Bug: T383557