Remove unused bind=True and self parameter from update_config

Author: mn-ram

openwisp_controller/connection/tasks.py

@@ -36,8 +36,8 @@ def _release_update_config_lock(device_id):
     cache.delete(lock_key)
 
 
-@shared_task(bind=True)
-def update_config(self, device_id):
+@shared_task
+def update_config(device_id):
     """
     Launches the ``update_config()`` operation
     of a specific device in the background