chore(deps): bump docker/build-push-action from 6.13.0 to 6.15.0

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 6.13.0 to 6.15.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v6.13.0...v6.15.0)

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

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

Author: dependabot[bot]

.github/workflows/build-verify.yml

@@ -63,7 +63,7 @@ jobs:
 
       - name: Build and push container image
         id: build-and-push
-        uses: docker/build-push-action@v6.13.0
+        uses: docker/build-push-action@v6.15.0
         if: github.repository_owner == 'microcks' && env.PACKAGE_IMAGE == 'true'
         with:
           context: .