do not error on aiohttp warning

Author: miguelgrinberg

setup.cfg

@@ -11,5 +11,6 @@ filterwarnings =
     error
     ignore:Legacy index templates are deprecated in favor of composable templates.:elasticsearch.exceptions.ElasticsearchWarning
     ignore:datetime.datetime.utcfromtimestamp\(\) is deprecated and scheduled for removal in a future version..*:DeprecationWarning
+    default:enable_cleanup_closed ignored.*:DeprecationWarning
 markers =
     sync: mark a test as performing I/O without asyncio.