我想安装 Docky。如何删除“Err:5 http://ppa.launchpad.net/docky-core/stable/ubuntu focal Release 404 Not Found [IP: 91.189.95.85 80]”？

Question

我想在 Ubuntu 20.04 上安装“Docky”，但是每次尝试添加源存储库时，都会收到错误。

这就是我尝试添加存储库的方式：

sudo add-apt-repository ppa:docky-core/stable

结果如下：

Ign:1 http://ppa.launchpad.net/docky-core/stable/ubuntu focal InRelease                                                                                                               
Get:2 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]                                                                                                             
Hit:3 http://in.archive.ubuntu.com/ubuntu focal InRelease                                                                                                                         
Err:5 http://ppa.launchpad.net/docky-core/stable/ubuntu focal Release                                  
  404  Not Found [IP: 91.189.95.85 80]
Hit:6 http://in.archive.ubuntu.com/ubuntu focal-updates InRelease                                      
Hit:7 http://in.archive.ubuntu.com/ubuntu focal-backports InRelease    
Hit:8 https://dl.winehq.org/wine-builds/ubuntu focal InRelease
Reading package lists... Done
E: The repository 'http://ppa.launchpad.net/docky-core/stable/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.

我该如何解决这个错误？