run make docker-push in a separate step after merge

Change-Id: Iad5866932b19b59e16e060d44e7777a8b3421192

Author: andmat900

.github/workflows/generate-manifest.yml

@@ -36,9 +36,15 @@ jobs:
           [ "$VERSION" == "main" ] && VERSION=$(echo ${{ github.sha }} | cut -c1-8)
           echo IMAGE_ID=$IMAGE_ID
           echo VERSION=$VERSION
+          echo "IMAGE_ID=$IMAGE_ID" >> $GITHUB_ENV
+          echo "VERSION=$VERSION" >> $GITHUB_ENV
           make docker-build docker-push split-installer IMG=$IMAGE_ID:$VERSION
           mkdir -p manifests/controller
           cp dist/* manifests/controller/
+      - name: Push docker image
+        if: github.event.pull_request.merged == true
+        run: |
+          make docker-push IMG=$IMAGE_ID:$VERSION
       - name: Commit changes
         run: |
           git config --global user.name 'github-actions[bot]'