remove directory entry

Author: coryallegory

DIRECTORY.md

@@ -650,8 +650,6 @@
     * [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_67/sol1.py)
   * Problem 76
     * [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_76/sol1.py)
-  * Problem 89
-    * [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_89/sol1.py)
   * Problem 97
     * [Sol1](https://github.com/TheAlgorithms/Python/blob/master/project_euler/problem_97/sol1.py)
   * Problem 99