If you are adding keys from a new GitHub profile, you have to add the username to /ansible/group_vars/all/users.yml.
Remember: If you want to revoke a key's access, do not simply delete the
user from the users.yml, but first set the "state" to
"absent". After that, you can delete the entry from the list. If you do not
set the state to "absent" first, the key will not be deleted from the
server you deploy on.