chore(ci): declare workflow outputs

Signed-off-by: Nathan Klick <[email protected]>

.github/workflows/zxc-publish-production-image.yaml

@@ -22,7 +22,9 @@ on:
         type: string
         default: "GCP"
     outputs:
-
+      docker-image:
+        description: "Docker Image:"
+        value: ${{ jobs.publish-image.outputs.docker-image }}
 
 defaults:
   run:
@@ -39,6 +41,8 @@ jobs:
   publish-image:
     name: ${{ inputs.custom-job-name || 'GCP' }}
     runs-on: [self-hosted, Linux, large, ephemeral]
+    outputs:
+      docker-image: ${{ steps.set-registry.outputs.docker-tag-base }}/hedera-network-node:${{ inputs.version }}
     steps:
       - name: Checkout Code
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1