In Ruby projects that publish a Gem, it is customary to NOT check Gemfile.lock into the repo.

Source: https://github.com/github/gitignore/blob/4488915eec0b3a45b5c63ead28f286819c0917de/Ruby.gitignore#L46-L50

It can be helpful to review the Gemfile.lock for debugging. So perhaps this could be an option in this action.