Add shell optional property to github_users

[andp97]

Set a custom shell for a user that I've added with this Ansible role.

Example:

- hosts: servers

  vars:
    github_users:
      - name: geerlingguy
        shell: /bin/zsh

[github-actions[bot]]

This pr has been marked 'stale' due to lack of recent activity. If there is no further activity, the issue will be closed in another 30 days. Thank you for your contribution!

Please read this blog post to see the reasons why I mark issues as stale.

[github-actions[bot]]

This pr has been closed due to inactivity. If you feel this is in error, please reopen the issue or file a new issue with the relevant details.