fix shutting down freezing (#178)

Author: lesnik512

packages/faststream-stomp/faststream_stomp/broker.py

@@ -160,7 +160,6 @@ async def stop(
             await sub.stop()
         if self._connection:
             await self._connection.__aexit__(exc_type, exc_val, exc_tb)
-        self._stopping = False
         self.running = False
 
     async def ping(self, timeout: float | None = None) -> bool: