Ensure a ref is passed to cherry_pick
This would have prevented confusing errors from https://gitlab.com/gitlab-org/release-tools/-/issues/431 and https://gitlab.com/gitlab-org/release-tools/-/issues/414.
This would have prevented confusing errors from https://gitlab.com/gitlab-org/release-tools/-/issues/431 and https://gitlab.com/gitlab-org/release-tools/-/issues/414.