remove need for mypy override

src/allmydata/test/test_storage_http.py

@@ -27,7 +27,8 @@ from queue import Queue
 from pycddl import ValidationError as CDDLValidationError
 from hypothesis import assume, given, strategies as st, settings as hypothesis_settings
 from fixtures import Fixture, TempDir, MonkeyPatch
-from treq.testing import StubTreq
+from treq.client import HTTPClient
+from treq.testing import StubTreq, RequestTraversalAgent
 from klein import Klein
 from hyperlink import DecodedURL
 from collections_extended import RangeMap
@@ -714,9 +715,11 @@ class GenericHTTPAPITests(SyncTestCase):
         If nothing is given in the ``Authorization`` header at all an
         ``Unauthorized`` response is returned.
         """
-        client = StubTreq(self.http.http_server.get_resource())
+        client = HTTPClient(
+            RequestTraversalAgent(self.http.http_server.get_resource())
+        )
         response = self.http.result_of_with_flush(
-            client.request(  # type: ignore[attr-defined]
+            client.request(
                 "GET",
                 "http://127.0.0.1/storage/v1/version",
             ),