Run redfish victoria job on focal

The ironic-standalone-redfish-victoria job is using latest tinyipa
based on tinycore 11.x, but still running on bionic.
That causes issues during the ipa-ramdisk build because of kernel
too old in bionic, so setting nodeset to focal.

Change-Id: Ia0fbc97184a4098635085edbdd6d7be5dfd2218c
diff --git a/zuul.d/stable-jobs.yaml b/zuul.d/stable-jobs.yaml
index dcc2df4..ee0e524 100644
--- a/zuul.d/stable-jobs.yaml
+++ b/zuul.d/stable-jobs.yaml
@@ -19,6 +19,7 @@
 - job:
     name: ironic-standalone-redfish-victoria
     parent: ironic-standalone-redfish
+    nodeset: openstack-single-node-focal
     override-checkout: stable/victoria
 
 - job: