build(deps): 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] <[email protected]>

.github/workflows/publish.yml

@@ -107,7 +107,7 @@ jobs:
         with:
           platforms: linux/amd64,linux/arm64
       - name: Build and publish model-server Docker image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         env:
           # We only push the resulting image when we are on release tag (i.e., the only time we have a push event) or on
           # manual request via the workflow_dispatch event.