Add no cover pragma on pytest.fail in tests/middleware/test_base.py

Co-authored-by: Adrian Garcia Badaracco <1755071+adriangb@users.noreply.github.com>

tests/middleware/test_base.py

@@ -297,7 +297,7 @@ async def cancel_on_disconnect():
             )
             pytest.fail(
                 "http.disconnect should have been received and canceled the scope"
-            )
+            )  # pragma: no cover
 
     app = DiscardingMiddleware(downstream_app)