Update squeezebox.py (#7617)

Do not fail in case no players are connected, in which case squeezeserver will return a result without player_loop.

homeassistant/components/media_player/squeezebox.py

@@ -95,7 +95,7 @@ class LogitechMediaServer(object):
         result = []
         data = yield from self.async_query('players', 'status')
 
-        for players in data['players_loop']:
+        for players in data.get('players_loop', []):
             player = SqueezeBoxDevice(
                 self, players['playerid'], players['name'])
             yield from player.async_update()