Teams SSH doesn't update existing users' SSH keys

首先定位 teams-ssh 的更新循环，以及读取 Github 团队成员关系和用户 SSH 密钥的代码。确认现有用户在 authorized_keys 中的表示方式，然后将完成条件定义为：能够检测并添加新增加的密钥，而不需要更改团队成员关系；密钥移除明确留作设计问题。

If someone is added to the Sudo or SSH teams in the HacKSU org, and later adds SSH key(s) to their account in order to log in to a server, the new keys will not be added to their .ssh/authorized_keys file, since that file is only updated when the user account is initially added to the server.

This can be worked around by removing a user from both the SSH and, if necessary, the Sudo team, waiting for teams-ssh to update, and then re-adding them and waiting for teams-ssh to update again.

Fixing this would require pulling each user's SSH keys along with their team membership from Github every 60 seconds, checking if each key is already present in the authorized_keys file or not, and adding it if it isn't already there.

Automatically removing keys when they're removed from a user's Github profile could be more problematic. It would increase the security of the system by providing a quick way to remove keys if they're compromised, but it could also lead to unexpected lockouts if the user uses an SSH key for their server account without even realizing it's also saved in their Github account.