运行命令时sudo apt update，我遇到了以下让我很困扰的问题：
$ sudo apt update
Hit:1 http://repo.mysql.com/apt/ubuntu eoan InRelease
Hit:2 https://deb.debian.org/debian buster InRelease
Ign:3 http://ppa.launchpad.net/morphis/anbox-support/ubuntu hirsute InRelease
Hit:4 https://deb.debian.org/debian-security buster/updates InRelease
Hit:5 https://download.sublimetext.com apt/stable/ InRelease
Ign:6 https://storage.googleapis.com/cros-packages/88 buster InRelease
Err:7 http://ppa.launchpad.net/morphis/anbox-support/ubuntu hirsute Release
404 Not Found [IP: 91.189.95.85 80]
Hit:8 https://storage.googleapis.com/cros-packages/88 buster Release
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/morphis/anbox-support/ubuntu hirsute 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: …apt ×1