先备份apt源配置
mv /etc/apt/sources.list /etc/apt/sources.list.old
编辑sources.list文件，vim /etc/apt/sources.list
deb http://deb.debian.org/debian bullseye main deb-src http://deb.debian.org/debian bullseye main deb http://deb.debian.org/debian-security/ bullseye-security main deb-src http://deb.debian.org/debian-security/ bullseye-security main deb http://deb.debian.org/debian bullseye-updates main deb-src http://deb.debian.org/debian bullseye-updates main
如果需要 contrib 和 non-free 组件，请在 main 之后添加 contrib non-free。
deb http://deb.debian.org/debian bullseye main contrib non-free deb-src http://deb.debian.org/debian bullseye main contrib non-free deb http://deb.debian.org/debian-security/ bullseye-security main contrib non-free deb-src http://deb.debian.org/debian-security/ bullseye-security main contrib non-free deb http://deb.debian.org/debian bullseye-updates main contrib non-free deb-src http://deb.debian.org/debian bullseye-updates main contrib non-free
如果需要 Backports、contrib 和非自由组件，请添加 bullseye-backports 行
eb http://deb.debian.org/debian bullseye-backports main contrib non-free deb-src http://deb.debian.org/debian bullseye-backports main contrib non-free
其它更多请参考官方说明：
https://wiki.debian.org/SourcesList