Deprecation warning related to deployer_user tasks

[keeganbrown]

At some point this should probably be addressed.
Under TASK [deployer_user ....

[DEPRECATION WARNING]: Using bare variables is deprecated. Update your playbooks so that the environment value uses the full variable syntax
('{{deployer_user.groups}}').
This feature will be removed in a future release. Deprecation warnings can be disabled by setting deprecation_warnings=False in
ansible.cfg.