centos已經不能安裝Certbot, 須改用snapd安裝

請先安裝 snapd https://kafeiou.pw/2021/02/17/3008/

sudo yum remove certbot
sudo yum install httpd mod_ssl
setsebool -P httpd_can_network_connect true
sudo snap install --classic certbot
sudo ln -s /snap/bin/certbot /usr/bin/certbot