Add locking for multiple reciever

src/nanobot.py

@@ -14,6 +14,7 @@ class Nanobot:
     def __init__(self):
         self._ws = None
         self._chat_id = None
+        self._lock = asyncio.Lock()
 
     async def __aenter__(self):
         await self.connect()
@@ -30,6 +31,7 @@ class Nanobot:
         main_logger.info("connected chat_id=%s", self._chat_id)
 
     async def chat(self, message: str, timeout: float = 60):
+        async with self._lock:
             try:
                 await self._ws.send(json.dumps({"content": message}))
             except websockets.ConnectionClosed: