Update docker/setup-buildx-action action to v3 (#5417)

Signed-off-by: milkmaker <milkmaker@mailcow.de>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/rebuild_backup_image.yml

@@ -17,7 +17,7 @@ jobs:
         uses: docker/setup-qemu-action@v3
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v2
+        uses: docker/setup-buildx-action@v3
 
       - name: Login to Docker Hub
         uses: docker/login-action@v3