尝试运行 apt update 时出现以下错误：
sudo apt update
Hit:1 http://ro-mirrors.evowise.com/ubuntu focal InRelease
Hit:2 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:3 http://ro-mirrors.evowise.com/ubuntu focal-backports InRelease
Hit:4 http://ro-mirrors.evowise.com/ubuntu focal-updates InRelease
Hit:5 http://ppa.launchpad.net/bashtop-monitor/bashtop/ubuntu focal InRelease
Hit:6 http://security.ubuntu.com/ubuntu focal-security InRelease
Hit:7 http://archive.canonical.com/ubuntu focal InRelease
Hit:8 http://ppa.launchpad.net/cappelikan/ppa/ubuntu focal InRelease
Err:9 http://ppa.launchpad.net/wireguard/wireguard/ubuntu focal InRelease
403 Forbidden [IP: 91.189.95.83 80]
Reading package lists... Done
E: Failed to fetch http://ppa.launchpad.net/wireguard/wireguard/ubuntu/dists/focal/InRelease 403 Forbidden [IP: 91.189.95.83 80]
E: The repository 'http://ppa.launchpad.net/wireguard/wireguard/ubuntu focal InRelease' is no longer signed.
N: Updating from such a repository can't be …