fixed python idioms url (#8543)

Co-authored-by: Biswas <rajdeep.biswas@sap.com>

books/free-programming-books-langs.md

@@ -1954,7 +1954,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [Python for Informatics: Exploring Information](http://www.pythonlearn.com/book.php) - Charles Russell Severance (2.7.5)
 * [Python for you and me](http://pymbook.readthedocs.org/en/latest/) (2.7.3)
 * [Python for you and me](http://pymbook.readthedocs.org/en/py3/) (3.x)
-* [Python Idioms](http://safehammad.com/downloads/python-idioms-2014-01-16.pdf) (PDF)
+* [Python Idioms](https://bennuttall.com/files/python-idioms-2014-01-16.pdf) (PDF)
 * [Python in Education](https://www.oreilly.com/ideas/python-in-education) - Nicholas Tollervey
 * [Python in Hydrology](http://www.greenteapress.com/pythonhydro/pythonhydro.html) - Sat Kumar Tomer
 * [Python Koans](https://github.com/gregmalcolm/python_koans) (2.7 or 3.x)