add centos 9 to ci

Author: zilchms

.github/workflows/ci.yml

@@ -69,6 +69,8 @@ jobs:
         setfile:
           - name: CentOS 8
             value: centos8-64vpnserver.ma{hostname=vpnserver}-centos8-64vpnclienta.a{hostname=vpnclienta}
+          - name: CentOS 9
+            value: centos9-64vpnserver.ma{hostname=vpnserver}-centos9-64vpnclienta.a{hostname=vpnclienta}
           - name: Debian 11
             value: debian11-64vpnserver.ma{hostname=vpnserver}-debian11-64vpnclienta.a{hostname=vpnclienta}
           - name: Ubuntu 20.04