workflows: Follow CentOS 7 repo change due to EOL

Signed-off-by: Hiroshi Hatake <[email protected]>

.github/workflows/build.yaml

@@ -60,10 +60,11 @@ jobs:
     steps:
       - name: Set up base image dependencies
         run: |
+          sed -i -e "s/^mirrorlist=http:\/\/mirrorlist.centos.org/#mirrorlist=http:\/\/mirrorlist.centos.org/g" /etc/yum.repos.d/CentOS-Base.repo
+          sed -i -e "s/^#baseurl=http:\/\/mirror.centos.org/baseurl=http:\/\/vault.centos.org/g" /etc/yum.repos.d/CentOS-Base.repo
           yum -y update
           yum install -y ca-certificates cmake gcc gcc-c++ make wget
-          wget http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
-          rpm -ivh epel-release-latest-7.noarch.rpm
+          yum install epel-release
           yum install -y cmake3
         shell: bash