fix: pass Message as positional arg to Agent.run()

Change agent.run(messages=Message(...)) to agent.run(Message(...)) to
match the expected positional signature and avoid potential TypeError.

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

Author: Prachig-Microsoft

src/ContentProcessor/src/libs/pipeline/handlers/map_handler.py

@@ -263,7 +263,7 @@ async def execute(self, context: MessageContext) -> StepResult:
             run_options = {"logprobs": True, "top_logprobs": 5}
 
         gpt_response = await agent.run(
-            messages=Message(
+            Message(
                 "user",
                 contents=self._to_agent_framework_contents(user_content),
             ),