Update mongo.py (#857)

TypeError: to_list() missing 1 required positional argument: 'length'

aiogram/contrib/fsm_storage/mongo.py

@@ -213,5 +213,5 @@ async def get_states_list(self) -> List[Tuple[int, int]]:
         :return: list of tuples where first element is chat id and second is user id
         """
         db = await self.get_db()
-        items = await db[STATE].find().to_list()
+        items = await db[STATE].find().to_list(length=None)
         return [(int(item['chat']), int(item['user'])) for item in items]