restore to ubuntu20.04

Dockerfile

@@ -1,6 +1,6 @@
-FROM ubuntu:22.04
+FROM ubuntu:20.04
 
-ADD docker/sources.list /etc/apt/sources.list
+ADD docker/ubuntu20_sources.list /etc/apt/sources.list
 
 RUN echo 'Asia/Shanghai' >/etc/timezone
 

docker/sources.list

@@ -1,16 +0,0 @@
-# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
-deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy main restricted universe multiverse
-# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy main restricted universe multiverse
-deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
-# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse
-deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
-# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse
-deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
-# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-security main restricted universe multiverse
-
-# 预发布软件源，不建议启用
-# deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-proposed main restricted universe multiverse
-# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-proposed main restricted universe multiverse
-
-
-deb https://repo.huaweicloud.com/ubuntu/ jammy main universe restricted multiverse

docker/ubuntu20_sources.list

@@ -0,0 +1,10 @@
+deb http://mirrors.cloud.tencent.com/ubuntu/ focal main restricted universe multiverse
+deb http://mirrors.cloud.tencent.com/ubuntu/ focal-security main restricted universe multiverse
+deb http://mirrors.cloud.tencent.com/ubuntu/ focal-updates main restricted universe multiverse
+#deb http://mirrors.cloud.tencent.com/ubuntu/ focal-proposed main restricted universe multiverse
+#deb http://mirrors.cloud.tencent.com/ubuntu/ focal-backports main restricted universe multiverse
+deb-src http://mirrors.cloud.tencent.com/ubuntu/ focal main restricted universe multiverse
+deb-src http://mirrors.cloud.tencent.com/ubuntu/ focal-security main restricted universe multiverse
+deb-src http://mirrors.cloud.tencent.com/ubuntu/ focal-updates main restricted universe multiverse
+#deb-src http://mirrors.cloud.tencent.com/ubuntu/ focal-proposed main restricted universe multiverse
+#deb-src http://mirrors.cloud.tencent.com/ubuntu/ focal-backports main restricted universe multiverse