Fixed problem with removing events during clean up

Signed-off-by: Aryaz Eghbali <eghbali.aryaz@gmail.com>

Author: AryazE

openleadr/client.py

@@ -1007,7 +1007,8 @@ async def _event_cleanup(self):
         """
         Periodic task that will clean up completed and cancelled events in our memory.
         """
-        for event in self.received_events:
+        for i in range(len(self.received_events)-1, -1, -1):
+            event = self.received_events[i]
             if event['event_descriptor']['event_status'] == 'cancelled' or \
                     utils.determine_event_status(event['active_period']) == 'completed':
                 logger.info(f"Removing event {event} because it is no longer relevant.")