使用 阿里云源 替换 ubuntu官方源
需要注意一点是 树莓派使用ARM处理器，库和普通ubuntu库不一样
普通使用 http://mirrors.aliyun.com/ubuntu/
ARM版使用 http://mirrors.aliyun.com/ubuntu-ports/
1，备份 sources.list 文件
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
2，使用 vim 编辑 sources.list 文件
sudo vim /etc/apt/sources.list
3，查看系统版本
lsb_release -a
4，根据系统版本，找到对应的源配置
https://developer.aliyun.com/mirror/ubuntu
把所有 ubuntu 替换为 ubuntu-ports
下面是替换好的 ubuntu 20.04(focal) 配置
deb http://mirrors.aliyun.com/ubuntu-ports/ focal main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports/ focal main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu-ports/ focal-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports/ focal-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu-ports/ focal-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports/ focal-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu-ports/ focal-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports/ focal-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu-ports/ focal-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports/ focal-backports main restricted universe multiverse
如果配置的不是ARM版会报错
binary-arm64/Packages 404