这是我sudo apt update在 16.04 上的输出（缩短的）：
[...]
Ign:2 http://screenshots.getdeb.net xenial-getdeb InRelease
[...]
Err:13 http://screenshots.getdeb.net xenial-getdeb Release
403 Forbidden [IP: 104.28.24.125 80]
[...]
Reading package lists... Done
E: The repository 'http://archive.getdeb.net/ubuntu xenial-getdeb 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.
我已按照说明手动配置了 GetDeb 存储库这里通过创建包含以下行的文件/etc/apt/sources.list.d/getdeb-apps.list：
deb http://archive.getdeb.net/ubuntu xenial-getdeb apps
直到今天，这已经持续了几个月了。
这里可能存在什么问题？我能在我这边修复它吗？或者这是他们的服务器上的错误？