feat(cmd/ci): make lstn ci run also on GitHub events different that pull_request

[leodido]

Since lstn ci job is to spawn argus's systemd service there's no reason to block it on GitHub events that are not referring to pull requests.

I kept it blocked on forked pull requests instead (at least until I have a clearer vision on this).

Ref #265

• I have read the contributing guidelines
• I have followed the coding guidelines
• I have written unit tests
• I have made sure that the pull request is of reasonable size and can be easily reviewed