Replace centos with rocky

CentOS no longer updates its image on Docker Hub, and it is nearly at the end of its life.

build-rocky.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+source common.sh
+docker-tags rockylinux |
+while read tag; do
+    dockerfile=$(mktemp)
+    cat << EOF > $dockerfile
+FROM rockylinux:$tag
+RUN sed -i \
+    -e 's/mirrorlist/#mirrorlist/g' \
+    -e 's/#baseurl/baseurl/g' \
+    -e 's|dl.rockylinux.org/\$contentdir|mirrors.ustc.edu.cn/rocky|g' \
+    /etc/yum.repos.d/Rocky-*.repo || \
+    sed -i \
+    -e 's/mirrorlist/#mirrorlist/g' \
+    -e 's/#baseurl/baseurl/g' \
+    -e 's|dl.rockylinux.org/\$contentdir|mirrors.ustc.edu.cn/rocky|g' \
+    /etc/yum.repos.d/rocky*.repo
+EOF
+    docker build -f $dockerfile -t ustclug/rocky:$tag .
+    docker push ustclug/rocky:$tag
+    rm $dockerfile
+done