Bump docker/build-push-action from 5 to 6

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 5 to 6.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v5...v6)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/release.yaml

@@ -121,7 +121,7 @@ jobs:
           docker login -u "${{ secrets.QUAY_USERNAME }}" -p "${{ secrets.QUAY_PASSWORD }}" quay.io
 
       - name: Build and push image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           build-args: |
             vncserver=${{ matrix.vncserver }}