[Bugfix] Consistent ascii handling in tool parsers (vllm-project#18883)

Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>
Signed-off-by: amit <amit.man@gmail.com>

Author: chaunceyjiang

vllm/entrypoints/openai/serving_chat.py

@@ -988,7 +988,8 @@ async def chat_completion_full_generator(
                     tool_calls=[
                         tool_call_class(function=FunctionCall(
                             name=tool_call.name,
-                            arguments=json.dumps(tool_call.parameters)))
+                            arguments=json.dumps(tool_call.parameters,
+                                                 ensure_ascii=False)))
                         for tool_call in tool_calls
                     ])