jobs/dependency-packages: Add GitLab support for building debian deps
Debian dependencies packages will be built when pushing gbp buildpackage tags on the associated gitlab repositories.
See https://gitlab-staging.swh.network/swh/infra/ci-cd/debs/python3-keycloak/-/tags for instance.
Depends on !120 (closed)
Migrated from D8999 (view on Phabricator)