Adapter tests are H2.

Author: Lukasa

test/test_integration.py

@@ -449,6 +449,9 @@ def socket_handler(listener):
 
 
 class TestRequestsAdapter(SocketLevelTest):
+    # This uses HTTP/2.
+    self.h2 = True
+
     def test_adapter_received_values(self):
         self.set_up()