Added missing import asyncio to agent with plugin python (#11472)

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Co-authored-by: Evan Mattson <[email protected]>

Author: sphenry

README.md

@@ -132,6 +132,7 @@ await foreach (AgentResponseItem<ChatMessageContent> response
 Enhance your agent with custom tools (plugins) and structured output:
 
 ```python
+import asyncio
 from typing import Annotated
 from pydantic import BaseModel
 from semantic_kernel.agents import ChatCompletionAgent