ci: update to use not yet released image tagging stuff

.github/workflows/release.yaml

@@ -77,6 +77,24 @@ jobs:
       - name: Set up Docker Buildx (for multi-arch builds)
         uses: docker/setup-buildx-action@v3
 
+      - name: Make decisions to push etc.
+        id: decisions
+        run: |
+          if [ "${{ startsWith(github.ref, 'refs/tags/') || (github.ref == 'refs/heads/main') }}" = "true" ]; then
+              echo "push=true" >> $GITHUB_OUTPUT
+          else
+              echo "push=false" >> $GITHUB_OUTPUT
+          fi
+
+          # We provide image tags with -tigervnc and -turbovnc suffixes to allow
+          # for an explicit choice, but also ship with a default choice of
+          # TigerVNC.
+          if [ "${{ matrix.vncserver == 'tigervnc') ]; then
+              echo "suffix=<empty-string>,-${{ matrix.vncserver }}" >> $GITHUB_OUTPUT
+          else
+              echo "suffix=-${{ matrix.vncserver }}" >> $GITHUB_OUTPUT
+          fi
+
       # For builds triggered by a git tag 1.2.3, we calculate image tags like:
       # [{prefix}:1.2.3, {prefix}:1.2, {prefix}:1, {prefix}:latest]
       #
@@ -88,29 +106,17 @@ jobs:
         uses: jupyterhub/action-major-minor-tag-calculator@v3
         with:
           githubToken: ${{ secrets.GITHUB_TOKEN }}
-          prefix: |
-            quay.io/jupyterhub/jupyter-remote-desktop-proxy:
-          suffix: |
-            
-            ${{ matrix.vncserver }}
+          prefix: "quay.io/jupyterhub/jupyter-remote-desktop-proxy:"
+          suffix: ${{ steps.decisions.outputs.suffix }}
           branchRegex: ^\w[\w-.]*$
           defaultTag: quay.io/jupyterhub/jupyter-remote-desktop-proxy:noref
 
-      - name: Decide to push or not
-        id: push_decision
-        run: |
-          if [ "${{ startsWith(github.ref, 'refs/tags/') || (github.ref == 'refs/heads/main') }}" = "true" ]; then
-              echo "push=true" >> $GITHUB_OUTPUT
-          else
-              echo "push=false" >> $GITHUB_OUTPUT
-          fi
-
       - name: Login to container registry
         # Credentials to Quay.io was setup by...
         # 1. Creating a [Robot Account](https://quay.io/organization/jupyterhub?tab=robots)
         # 2. Giving it push permissions to the image repository
         # 3. Adding Robot Account credentials as workflow environment secrets
-        if: steps.push_decision.outputs.push == 'true'
+        if: steps.decisions.outputs.push == 'true'
         run: |
           docker login -u "${{ secrets.QUAY_USERNAME }}" -p "${{ secrets.QUAY_PASSWORD }}" quay.io
 
@@ -121,5 +127,5 @@ jobs:
             vncserver=${{ matrix.vncserver }}
           context: .
           platforms: linux/amd64,linux/arm64
-          push: ${{ steps.push_decision.outputs.push == 'true' }}
+          push: ${{ steps.decisions.outputs.push }}
           tags: ${{ join(fromJson(steps.tags.outputs.tags)) }}