This patch changes the automerge config to use the gitlab native feature
of automerging changing using the "merge if CI pipeline success"
feature. This should prevent the current situation where automerge is
enabled but not used due to the fact that renovate bots runs as cronjob
instead of being the server-side application.
This will make sure that not just dependency files but also the lock
files will be managed by renovatebot, which should improve the ability
to automerge changes.
GitLab provides the API URL as a predefined enviornment variables for
each CI job. Therefore adding it to the config and using it there seems
very useful. It should also improve the protability of the repository.
