Update free-programming-playgrounds.md (#3868)

* Update free-programming-playgrounds.md

Added python interpreter

* Update free-programming-playgrounds.md

Fixed linter error

free-programming-playgrounds.md

@@ -150,6 +150,7 @@
 ### Python
 
 * [Codepad](http://codepad.org)
+* [Python Trinket](https://trinket.io/python)
 * [Python.org Shell](https://www.python.org/shell)