Pyupgrade to python3.8 (#3616)

* Upgrade to Python 3.8 syntax

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

data_structures/heap/heap.py

@@ -1,7 +1,7 @@
 #!/usr/bin/python3
 
 
-class Heap(object):
+class Heap:
     """
     >>> unsorted = [103, 9, 1, 7, 11, 15, 25, 201, 209, 107, 5]
     >>> h = Heap()