Bump docker/build-push-action from 5 to 6 in the ci group

Bumps the ci group with 1 update: [docker/build-push-action](https://github.com/docker/build-push-action).


Updates `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
  dependency-group: ci
...

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

.github/workflows/release.yaml

@@ -40,7 +40,7 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - name: Build and push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           tags: ghcr.io/external-secrets/bitwarden-sdk-server:${{ steps.prep.outputs.VERSION }}
           push: true