update common Gemfile for chef11+12
update common Gemfile for chef11+12

michaelklishin/chef-ssh-hardening,hardening-io/chef-ssh-hardening,hardening-io/chef-ssh-hardening,dev-sec/chef-ssh-hardening,dev-sec/chef-ssh-hardening,patcon/chef-ssh-hardening,patcon/chef-ssh-hardening,michaelklishin/chef-ssh-hardening