chore: add type hints to pancake_sort

Author: abhi-zit77

sorts/pancake_sort.py

@@ -8,8 +8,10 @@
 python pancake_sort.py
 """
 
+from typing import Any
 
-def pancake_sort(arr):
+
+def pancake_sort(arr: list[Any]) -> list[Any]:
     """Sort Array with Pancake Sort.
     :param arr: Collection containing comparable items
     :return: Collection ordered in ascending order of items