prevent empty migration warning (#2901)

src/Migrations/Version20191113132640.php

@@ -39,9 +39,12 @@ final class Version20191113132640 extends AbstractMigration
             $timesheetTags->removeForeignKey('FK_732EECA9BAD26311');
         }
         $timesheetTags->addForeignKeyConstraint('kimai2_tags', ['tag_id'], ['id'], ['onDelete' => 'CASCADE'], 'FK_732EECA9BAD26311');
+
+        $this->preventEmptyMigrationWarning();
     }
 
     public function down(Schema $schema): void
     {
+        $this->preventEmptyMigrationWarning();
     }
 }