DummyProtocol is not async (#2686)

Co-authored-by: Alex Ruddick <alex.ruddick@grantek.com>

Author: alexrudd2

test/transport/conftest.py

@@ -35,7 +35,7 @@ def callback_data(self, data: bytes, addr: tuple | None = None) -> int:
 
 
 @pytest.fixture(name="dummy_protocol")
-async def prepare_dummy_protocol():
+def prepare_dummy_protocol():
     """Return transport object."""
     return DummyProtocol