fix(test): add multimodal param to fake_responses_with_cache mock

The mock was missing the explicit multimodal parameter, causing it
to leak into **api_kwargs and fail the assertion.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Hiroki Mizukami

tests/pandas_ext/test_series_async.py

@@ -91,7 +91,7 @@ def fake_infer_schema(self, instructions: str, max_examples: int = 100, **api_kw
         captured["infer_kwargs"] = dict(api_kwargs)
         return SimpleNamespace(inference_prompt="inferred prompt", model=str)
 
-    async def fake_responses_with_cache(self, instructions: str, cache, response_format=str, **api_kwargs):
+    async def fake_responses_with_cache(self, instructions: str, cache, response_format=str, multimodal=False, **api_kwargs):
         captured["responses_kwargs"] = dict(api_kwargs)
         captured["instructions"] = instructions
         captured["response_format"] = response_format