fix: fix issue with the asyncqt event loop

Previously, we erroneously passed down the raw socket.socket instance to
loop.add_readre and loop.remove_reader. Now, we pass down a file descriptor.

Apparently, other event loops handle the socket.socket type just fine. Still,
this type is not part of the offical loop API.

See also: harvimt/quamash#71

asyncio_mqtt/client.py

@@ -242,11 +242,11 @@ def _on_publish(self, client, userdata, mid):
     def _on_socket_open(self, client, userdata, sock):
         def cb():
             client.loop_read()
-        self._loop.add_reader(sock, cb)
+        self._loop.add_reader(sock.fileno(), cb)
         self._misc_task = self._loop.create_task(self._misc_loop())
 
     def _on_socket_close(self, client, userdata, sock):
-        self._loop.remove_reader(sock)
+        self._loop.remove_reader(sock.fileno())
         with suppress(asyncio.CancelledError):
             self._misc_task.cancel()