Address CI comments (#347)

* remove deprecated set-output from workflow

* ensure CI testuser password cannot be present in fat images

.github/workflows/fatimage.yml

@@ -48,8 +48,6 @@ 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
@@ -60,5 +58,5 @@ jobs:
             sleep 30
           done
           IMAGE_NAME=$(openstack image show -f value -c name $IMAGE_ID)
-          echo "::set-output name=IMAGE_ID::$IMAGE_ID"
-          echo "::set-output name=IMAGE_NAME::$IMAGE_NAME"
+          echo "IMAGE_ID=${IMAGE_ID}" >> "$GITHUB_OUTPUT"
+          echo "IMAGE_NAME=${IMAGE_NAME}" >> "$GITHUB_OUTPUT"