Add focal nodeset

Change-Id: I4273ccf12e9691cfac45f7e4bb373a7eef1c508f
diff --git a/zuul.d/nodesets.yaml b/zuul.d/nodesets.yaml
index 1da2f05..e94ed89 100644
--- a/zuul.d/nodesets.yaml
+++ b/zuul.d/nodesets.yaml
@@ -1,4 +1,10 @@
 - nodeset:
+    name: ubuntu-focal
+    nodes:
+      - name: ubuntu-focal
+        label: focal-2c-8g
+
+- nodeset:
     name: ubuntu-jammy
     nodes:
       - name: ubuntu-jammy