Fix: Reset _closing flag on WebSocket reconnection to ensure on_client_disconnected fires

The on_client_disconnected event handler was not firing after the first
disconnection in long-running containers. The _closing flag was set to True
on first disconnect and never reset, preventing subsequent disconnect events
from being triggered.

This fix resets the _closing flag to False in the setup() method, ensuring
each new connection starts with a clean state.

src/pipecat/transports/websocket/fastapi.py

@@ -105,6 +105,8 @@ class FastAPIWebsocketClient:
             _: The start frame (unused).
         """
         self._leave_counter += 1
+        # Reset closing flag when setting up a new connection
+        self._closing = False
 
     def receive(self) -> typing.AsyncIterator[bytes | str]:
         """Get an async iterator for receiving WebSocket messages.