Drop unsupported `warn` in command/shell
    
    This is needed to support newer Ansible.
    The `warn` module param was removed.
    
    See:
    
    https://github.com/ansible/ansible/blob/stable-2.14/changelogs/CHANGELOG-v2.14.rst
    
    ```
    command/shell - remove deprecated warn module param
    ```
    
    Signed-off-by: Miroslav Vadkerti <mvadkert@redhat.com>