问题描述：
某一天，突然apt install下载不了软件包了。
然后sudo apt update竟然也无效了，出现了一堆错误：
忽略:1 https://mirrors.ustc.edu.cn/ubuntu-ports jammy InRelease
忽略:2 https://mirrors.ustc.edu.cn/ubuntu-ports jammy-updates InRelease
忽略:3 https://mirrors.ustc.edu.cn/ubuntu-ports jammy-backports InRelease
忽略:4 https://mirrors.ustc.edu.cn/ubuntu-ports jammy-security InRelease
错误:5 https://mirrors.ustc.edu.cn/ubuntu-ports jammy Release
Certificate verification failed: The certificate is NOT trusted. The certificate chain uses not yet valid certificate. Could not handshake: Error in the certificate verification. [IP: 202.141.160.110 443]
命中:6 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu bionic InRelease
错误:7 https://mirrors.ustc.edu.cn/ubuntu-ports jammy-updates Release
Certificate verification failed: The certificate is NOT trusted. The certificate chain uses not yet valid certific