transports(fastapi): don't try to close socket

The websocket is passed from outside (in the transport constructor) so we should
not be trying to close it. FastAPI does actually close it later. We didn't see
any issue because these functions were not implemented properly. The value to
check was `application_state` instead of `client_state`. But in any case,
Pipecat should not be responsible for closing things passed from outside.

src/pipecat/transports/network/fastapi_websocket.py

@@ -70,16 +70,6 @@ class FastAPIWebsocketInputTransport(BaseInputTransport):
         await self._callbacks.on_client_connected(self._websocket)
         self._receive_task = self.get_event_loop().create_task(self._receive_messages())
 
-    async def stop(self, frame: EndFrame):
-        await super().stop(frame)
-        if self._websocket.client_state != WebSocketState.DISCONNECTED:
-            await self._websocket.close()
-
-    async def cancel(self, frame: CancelFrame):
-        await super().cancel(frame)
-        if self._websocket.client_state != WebSocketState.DISCONNECTED:
-            await self._websocket.close()
-
     async def _receive_messages(self):
         async for message in self._websocket.iter_text():
             frame = self._params.serializer.deserialize(message)