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>

machine_learning/astar.py

@@ -13,7 +13,7 @@ is made.A* also known as the algorithm with brains
 import numpy as np
 
 
-class Cell(object):
+class Cell:
     """
     Class cell represents a cell in the world which have the property
     position : The position of the represented by  tupleof x and y
@@ -45,7 +45,7 @@ class Cell(object):
         print(self.position)
 
 
-class Gridworld(object):
+class Gridworld:
     """
     Gridworld class represents the  external world here a grid M*M
     matrix