updating DIRECTORY.md

Author: github-actions

DIRECTORY.md

@@ -585,6 +585,7 @@
   * [Hardy Ramanujanalgo](maths/hardy_ramanujanalgo.py)
   * [Hexagonal Number](maths/hexagonal_number.py)
   * [Integration By Simpson Approx](maths/integration_by_simpson_approx.py)
+  * [Interquartile Range](maths/interquartile_range.py)
   * [Is Int Palindrome](maths/is_int_palindrome.py)
   * [Is Ip V4 Address Valid](maths/is_ip_v4_address_valid.py)
   * [Is Square Free](maths/is_square_free.py)