add KUBECTL_SHA256 to environment for passthru

We also need to add KUBECTL_SHA256 of the job environment for the
digest passthru to work.

Change-Id: I6c7a6afac76144f156e8dcd7364b80bb36d530e7
diff --git a/jjb/metal3/job_openstack_image_building.yml b/jjb/metal3/job_openstack_image_building.yml
index aadee7f..ba02f46 100644
--- a/jjb/metal3/job_openstack_image_building.yml
+++ b/jjb/metal3/job_openstack_image_building.yml
@@ -24,6 +24,8 @@
 # This job can be triggered manually or through a Github pull request. It creates a
 # pipeline job. The pipeline scripts are maintained in Nordix/metal3-dev-tools repository.
 
+# NOTE: KUBERNETES_VERSION and KUBECTL_SHA256 are changed as a pair
+
 - job-template:
     id: openstack_image_building
     name: '{job_prefix}_openstack_image_building'
@@ -38,6 +40,10 @@
         default: "v1.28.1"
         description: 'Kubernetes version'
     - string:
+        name: KUBECTL_SHA256
+        default: 'e7a7d6f9d06fab38b4128785aa80f65c54f6675a0d2abef655259ddd852274e1'  # v1.28.1
+        description: 'Kubectl SHA256 digest matching KUBERNETES_VERSION'
+    - string:
         name: KIND_NODE_IMAGE_VERSION
         default: "v1.28.0"
         description: 'Kind node container image version'