Fix GitHub Actions: Add setup-buildx-action

.github/workflows/docker-publish.yml

@@ -26,6 +26,10 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
+      # Set up Docker Buildx (required for caching)
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
       # Login against a Docker registry except on PR
       # https://github.com/docker/login-action
       - name: Log into registry ${{ env.REGISTRY }}