linter ignores playbooks

[SilasPeters]

The linter does not check ansible/playbooks/. I guess this is the case because they are more fragile, and we do not want to nudge people into changing them.

However, the playbooks use heavily outdated ansible code. Thus, we should run the linter manually some time, and/or start including these playbooks in the linter combined with enforcing that everything goes through a PR.