chore: follow up on enabling headers in tuning

PiperOrigin-RevId: 788151847

Author: wanlin31

google/genai/tunings.py

@@ -799,7 +799,9 @@ def _get(
     return_value = types.TuningJob._from_response(
         response=response_dict, kwargs=parameter_model.model_dump()
     )
-
+    return_value.sdk_http_response = types.HttpResponse(
+        headers=response.headers
+    )
     self._api_client._verify_response(return_value)
     return return_value
 
@@ -1147,7 +1149,9 @@ async def _get(
     return_value = types.TuningJob._from_response(
         response=response_dict, kwargs=parameter_model.model_dump()
     )
-
+    return_value.sdk_http_response = types.HttpResponse(
+        headers=response.headers
+    )
     self._api_client._verify_response(return_value)
     return return_value