Keep Rails 6 compatibility for "stable" version

Product Support
6

Didn’t find a convenient git command to do this but this below in container config did the trick :

hooks:
  after_code:
    - exec:
        cd: $home/plugins
        cmd:
          - git clone https://github.com/discourse/discourse-gamification && cd discourse-gamification && git checkout 48b2decfbefda6044953ca0413e45ca3cc18b156