GitLab

Use the first parent commit for changed files as fallback

See merge request omegacen/ci-templates!55

v5

Closes #8

See merge request omegacen/ci-templates!53

The CI job token has limited access to the API; cf.
https://docs.gitlab.com/ee/ci/jobs/ci_job_token.html

Otherwise, you cannot disable all CI jobs and enable just one.

Also, remove run/skip variables from MM and AST jobs. These do
not make sense there.