Degrade gcc-11 to gcc-5 on ubuntu22.04

 执行下面的一系列的指令，探索gccjiang

sudo gedit /etc/apt/sources.list 

add the following at the last line:
deb https://mirrors.cloud.tencent.com/ubuntu/ bionic main universe

then:
sudo apt-get update

Find error:
W: GPG 错误：http://mirrors.aliyun.com/ubuntu xenial-security InRelease: 由于没有公钥，无法验证下列签名： NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
E: 仓库 “http://mirrors.aliyun.com/ubuntu xenial-security InRelease” 没有数字签名。

then, import key:
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3B4FE6ACC0B21F32

find error again:
ethan@ethan-ThinkPad-T14-Gen-1:~$ apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 40976EAF437D05B5
Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).
Executing: /tmp/apt-key-gpghome.EeC8SQMV5u/gpg.1.sh --recv-keys --keyserver