出現：OSError: mysql_config not found
於是執行：yum install mysql-devel gcc gcc-devel python-devel
卻出現：Failed to download metadata for repo ‘appstream’: Cannot prepare internal mirrorlist: No URLs in mirrorlist
解決方案：CentOs Linux 8 从 2021.10.31 号后已经停止维护，所以之后更新镜像需要通过 vault.centos.org来获取更新
cd /etc/yum.repos.d/ sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-* sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*
解決！！！
接著執行：yum install mysql-devel gcc
安裝成功
執行：pip install mysqlclient
成功安裝！！！
安裝 django-simple-captcha 錯誤：
The headers or library files could not be found for jpeg
解決方案：yum -y install libjpeg-turbo-devel
