test: fix async showcase test

Author: parthea

tests/system/conftest.py

@@ -408,7 +408,7 @@ def intercepted_echo_grpc(use_mtls):
 
 
 @pytest.fixture
-def intercepted_echo_grpc_async():
+async def intercepted_echo_grpc_async():
     # The interceptor adds 'showcase-trailer' client metadata. Showcase server
     # echoes any metadata with key 'showcase-trailer', so the same metadata
     # should appear as trailing metadata in the response.

tests/system/test_response_metadata.py

@@ -95,7 +95,7 @@ async def test_metadata_response_unary_async(
         request_metadata = ("something3", "something_value3")
 
         if transport == "grpc_asyncio":
-            client, interceptor = intercepted_echo_grpc_async
+            client, interceptor = await intercepted_echo_grpc_async
         else:
             client, interceptor = intercepted_echo_rest_async
         response = await client.echo(