Adjust danger logic to only consider the current stable version
When validating if a merge request is targeting a branch inside the maintenance policy, Danger is verifying if the branch is targeting a version that is part of the last three GitLab versions. This logic was introduced when working on the extension of the maintenance policy. Since we decided against this extension, the logic should be updated to:
- Only consider the current stable branch
- If the merge request targets another stable branch, the backporting to older releases warning should show up: