debian 10 更换源 使用国内源 配置方法

配置前请先参考：
https://www.cnblogs.com/wswind/p/9881005.html

nano /etc/apt/sources.list

deb http://ftp.cn.debian.org/debian buster main
deb http://ftp.cn.debian.org/debian buster-updates main
deb http://ftp.cn.debian.org/debian-security/ buster/updates main
deb http://ftp.cn.debian.org/debian buster-backports main