Clean Code: Python

Fix issues found by flake8-bugbear:

* Unused loop variables
* assert statements in non-test code
* mixing test code with production code
* mark one excessive test which takes ~10min to run
  as 'slow'

04_Awari/python/awari.py

@@ -292,7 +292,7 @@ def do_move(m, home, board):
     move_stones = board[m]
     board[m] = 0
 
-    for stones in range(move_stones, 0, -1):
+    for _stones in range(move_stones, 0, -1):
         m = m + 1
         if m > 13:
             m = m - 14