fix: remove unused Channel import (ruff F401)

Author: lalit-videodb

videodb/capture_session.py

@@ -1,6 +1,6 @@
 from typing import List, Optional
 from videodb._constants import ApiPath
-from videodb.capture import Channel, VideoChannel, AudioChannel
+from videodb.capture import VideoChannel, AudioChannel
 from videodb.rtstream import RTStream