test(openai): add method to Responses stub in reasoning-params test

Author: Kairick

tests/unit/test_openai.py

@@ -1281,7 +1281,7 @@ def test_chat_completion_reasoning_parameters_absent_by_default(
 
 def test_responses_kwargs_capture_reasoning_parameters():
     data = lf_openai_module._get_langfuse_data_from_kwargs(
-        SimpleNamespace(type="chat", object="Responses"),
+        SimpleNamespace(type="chat", object="Responses", method="create"),
         {
             "model": "gpt-5",
             "input": "1 + 1 = ?",