PipelineTask: add IdleFrameObserver to detect idle pipelines

src/pipecat/tests/utils.py

@@ -8,7 +8,7 @@
 
 import asyncio
 from dataclasses import dataclass
-from typing import Any, Awaitable, Callable, Dict, List, Optional, Sequence, Tuple
+from typing import Awaitable, Callable, List, Optional, Sequence, Tuple
 
 from pipecat.frames.frames import (
     EndFrame,