GitService: Define a protected #_open_pull_request method

Author: neomilium

lib/modulesync/git_service/base.rb

@@ -19,6 +19,12 @@ def open_pull_request(repo_path:, namespace:, title:, message:, source_branch:,
           noop: noop,
         )
       end
+
+      protected
+
+      def _open_pull_request(repo_path:, namespace:, title:, message:, source_branch:, target_branch:, labels:, noop:) # rubocop:disable Metrics/ParameterLists, Metrics/LineLength
+        raise NotImplementedError
+      end
     end
   end
 end