deprecation warnings in Ansible 2.8

[sfuerte]

Actual behavior

[DEPRECATION WARNING]: evaluating ssh_hardening_enabled as a bare variable, this behaviour will go away and you might need to add |bool to the expression in the future. Also see CONDITIONAL_BARE_VARS
configuration toggle.. This feature will be removed in version 2.12. Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.

Example Playbook

...
  roles:
    - role: dev-sec.ssh-hardening
...

OS / Environment
Ansible Version

# ansible --version
ansible 2.8.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.5 (default, Mar 26 2019, 22:13:06) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]

Role Version

# ansible-galaxy list  | grep ssh-hard
- dev-sec.ssh-hardening, 6.1.1

same as in dev-sec/ansible-collection-hardening#221

[rndmh3ro]

Thanks @sfuerte for opening this issue.

As this seems easy to fix, I added the help-wanted label so anyone who wants to can create a PR!