Make rockylinux job non-voting

It is currently failing, let's unblock the CI until we have a fix.

Change-Id: I7f072ceef57c302eb6ce20e108043d2390e9f481
diff --git a/.zuul.yaml b/.zuul.yaml
index 8e20f6e..30e5397 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -726,6 +726,7 @@
     description: Rocky Linux 9 Blue Onyx platform test
     nodeset: devstack-single-node-rockylinux-9
     timeout: 9000
+    voting: false
     vars:
       configure_swap_size: 4096