由于我在 Debian 10 上安装了 certbot，它总是显示此错误：
root@HypeTime:/home/sinusbot# apt update
Hit:1 http://security.debian.org/debian-security buster/updates InRelease
Hit:2 http://deb.debian.org/debian buster InRelease
Hit:3 http://deb.debian.org/debian buster-updates InRelease
Ign:4 http://ppa.launchpad.net/certbot/certbot/ubuntu focal InRelease
Err:5 http://ppa.launchpad.net/certbot/certbot/ubuntu focal Release
404 Not Found [IP: 2001:67c:1560:8008::15 80]
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/certbot/certbot/ubuntu focal Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
有人知道如何解决这个错误吗？