我正在尝试注册我的 Ubuntu 订阅，但是失败了。
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.6 LTS
Release: 20.04
Codename: focal
$ sudo pro attach C12Ud8pBNhUTo5VNMhww2cXqywnk9U
[sudo] password for User:
Failed to attach machine. See https://ubuntu.com/pro/dashboard