updating DIRECTORY.md

Author: github-actions

DIRECTORY.md

@@ -529,6 +529,7 @@
   * [Perfect Square](https://github.com/TheAlgorithms/Python/blob/master/maths/perfect_square.py)
   * [Persistence](https://github.com/TheAlgorithms/Python/blob/master/maths/persistence.py)
   * [Pi Monte Carlo Estimation](https://github.com/TheAlgorithms/Python/blob/master/maths/pi_monte_carlo_estimation.py)
+  * [Points Are Collinear 3D](https://github.com/TheAlgorithms/Python/blob/master/maths/points_are_collinear_3d.py)
   * [Pollard Rho](https://github.com/TheAlgorithms/Python/blob/master/maths/pollard_rho.py)
   * [Polynomial Evaluation](https://github.com/TheAlgorithms/Python/blob/master/maths/polynomial_evaluation.py)
   * [Power Using Recursion](https://github.com/TheAlgorithms/Python/blob/master/maths/power_using_recursion.py)