(fix) OpenAI's optional messages[].name does not work with Mistral API (#6701)

* use helper for _transform_messages mistral

* add test_message_with_name to base LLMChat test

* fix linting

tests/llm_translation/test_mistral_api.py

@@ -0,0 +1,34 @@
+import asyncio
+import os
+import sys
+import traceback
+
+from dotenv import load_dotenv
+
+import litellm.types
+import litellm.types.utils
+from litellm.llms.anthropic.chat import ModelResponseIterator
+
+load_dotenv()
+import io
+import os
+
+sys.path.insert(
+    0, os.path.abspath("../..")
+)  # Adds the parent directory to the system path
+from typing import Optional
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+import litellm
+
+from litellm.llms.anthropic.common_utils import process_anthropic_headers
+from httpx import Headers
+from base_llm_unit_tests import BaseLLMChatTest
+
+
+class TestMistralCompletion(BaseLLMChatTest):
+    def get_base_completion_call_args(self) -> dict:
+        litellm.set_verbose = True
+        return {"model": "mistral/mistral-small-latest"}