fix: mark server_streaming method as async

gapic/templates/%namespace/%name_%version/%sub/services/%service/async_client.py.j2

@@ -192,7 +192,7 @@ class {{ service.async_client_name }}:
 
     {% for method in service.methods.values() %}
       {% with method_name = method.safe_name|snake_case + "_unary" if method.operation_service else method.safe_name|snake_case %}
-    {%+ if not method.server_streaming %}async {% endif %}def {{ method_name }}(self,
+    async def {{ method_name }}(self,
       {% endwith %}
             {% if not method.client_streaming %}
             request: Optional[Union[{{ method.input.ident }}, dict]] = None,
@@ -343,7 +343,7 @@ class {{ service.async_client_name }}:
 
         # Send the request.
         {%+ if not method.void %}response = {% endif %}
-        {% if not method.server_streaming %}await {% endif %}rpc(
+rpc(
             {% if not method.client_streaming %}
             request,
             {% else %}

gapic/templates/tests/unit/gapic/%name_%version/%sub/test_macros.j2

@@ -183,6 +183,7 @@ async def test_{{ method_name }}_async(transport: str = 'grpc_asyncio', request_
     message = await response.read()
     assert isinstance(message, {{ method.output.ident }})
     {% else %}
+    response = await response
     assert isinstance(response, {{ method.client_output_async.ident }})
     {% for field in method_output.fields.values() | rejectattr('message') %}
     {% if not field.oneof or field.proto3_optional %}