chore(deps): bump docker/build-push-action from 5 to 6 (#5)

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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/container-build.yml

@@ -64,7 +64,7 @@ jobs:
           echo "time-docker=$(date --utc +'%Y-%m-%dt%H-%M-%Sz')" >> $GITHUB_OUTPUT
 
       - name: Build and push image in production
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         if: github.event_name != 'pull_request' && github.ref == 'refs/heads/main'
         with:
           # directly push image
@@ -101,7 +101,7 @@ jobs:
             docker.io/zorrn/anki-sync-server:${{ steps.set-op.outputs.time-docker }}
 
       - name: Build image in testing only
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         if: github.event_name == 'pull_request'
         with:
           # do not push image