fix testuser password in CI image build

Author: sjpb

.github/workflows/fatimage.yml

@@ -48,6 +48,8 @@ jobs:
           cd packer/
           packer init .
           PACKER_LOG=1 packer build -only openstack.openhpc -on-error=${{ vars.PACKER_ON_ERROR }} -var-file=$PKR_VAR_environment_root/${{ vars.CI_CLOUD }}.pkrvars.hcl openstack.pkr.hcl
+        env:
+          TESTUSER_PASSWORD: ${{ secrets.TEST_USER_PASSWORD }}
 
       - name: Get created image name from manifest
         id: manifest