Fixed Python shebang and UTF-8 coding in modules

Be consistent with Ansible docs [1], [2], [3].

[1] https://docs.ansible.com/ansible/latest/dev_guide/developing_modules_documenting.html
[2] https://docs.ansible.com/ansible-core/devel/dev_guide/testing/sanity/shebang.html
[3] b86a18bd27/test/lib/ansible_test/_util/controller/sanity/code-smell/shebang.py

Change-Id: Ia3976bb3fcca662cefa219edeef057bcb7143c01

plugins/module_utils/openstack.py

@@ -1,3 +1,6 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
 # This code is part of Ansible, but is an independent component.
 # This particular file snippet, and this file snippet only, is BSD licensed.
 # Modules you write using this snippet, which is embedded dynamically by Ansible