Bump docker/metadata-action from 5 to 6

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

---
updated-dependencies:
- dependency-name: docker/metadata-action
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/release.yml

@@ -86,7 +86,7 @@ jobs:
 
       - name: Docker metadata for backend
         id: meta-backend
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: ghcr.io/${{ steps.vars.outputs.owner }}/nextjs-python-computer-vision-kit-backend
           tags: |
@@ -97,7 +97,7 @@ jobs:
 
       - name: Docker metadata for frontend
         id: meta-frontend
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: ghcr.io/${{ steps.vars.outputs.owner }}/nextjs-python-computer-vision-kit-frontend
           tags: |