Build and test on Rocky Linux

Author: pcolberg

.github/workflows/build-linux.yml

@@ -57,7 +57,7 @@ jobs:
     strategy:
       matrix:
         image:
-          - centos-8-dev
+          - rockylinux-8-dev
           - opensuse-leap-15-dev
           - ubuntu-18.04-dev
           - ubuntu-20.04-dev