Dangerfile: Fix undefined method

Changes introduced in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/40641 cause this
error:

undefined method has_database_scoped_labels?
from danger/database/Dangerfile:62

danger/database/Dangerfile

@@ -59,7 +59,7 @@ if gitlab.mr_labels.include?('database') || db_paths_to_review.any?
   markdown(DB_MESSAGE)
   markdown(DB_FILES_MESSAGE + helper.markdown_list(db_paths_to_review)) if db_paths_to_review.any?
 
-  unless has_database_scoped_labels?(gitlab.mr_labels)
+  unless helper.has_database_scoped_labels?(gitlab.mr_labels)
     gitlab.api.update_merge_request(gitlab.mr_json['project_id'],
                                     gitlab.mr_json['iid'],
                                     add_labels: 'database::review pending')