Appease ansible sanity

According to the following link, '#!/usr/bin/env python' should be OK.

https://docs.ansible.com/ansible/latest/dev_guide/testing/sanity/shebang.html

Let's try...

playbooks/files/dynamic_inventory.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #
 # Copyright (c) 2024 Cisco and/or its affiliates.
 #