fix test

Author: isabella-janssen

Diff for: machineconfiguration/v1alpha1/tests/machineconfignodes.machineconfiguration.openshift.io/MachineConfigNodes.yaml

@@ -80,6 +80,7 @@ tests:
           node:
             name: foobar
       expectedError: "spec.configVersion: Required value, <nil>: Invalid value: \"null\""
+  onUpdate:
     - name: PinnedImageSet desired generation must be greater than or equal to the current generation
       initial: |
         apiVersion: machineconfiguration.openshift.io/v1alpha1