Certbot: CentOS 7：没有可用的软件包 certbot。

我在 CentOS 7 上安装 certbot 时遇到了一点麻烦——我已经运行sudo yum install epel-release ：

[centos@jump-1 ~]$ sudo yum install epel-release
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.solarvps.com
 * epel: mirror.us.leaseweb.net
 * extras: mirrors.lga7.us.voxel.net
 * updates: mirror.datto.com
Package epel-release-7-6.noarch already installed and latest version
Nothing to do

但是sudo yum install certbot出现了：

[centos@jump-1 ~]$ sudo yum install certbot
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.solarvps.com
 * epel: mirror.symnds.com
 * extras: mirrors.lga7.us.voxel.net
 * updates: mirrors.advancedhosters.com
No package certbot available.
Error: Nothing to do

我应该尝试什么？