.github: Bump docker/build-push-action from 6.14.0 to 6.15.0 (#2178)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 6.14.0 to 6.15.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v6.14.0...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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/release.yml

@@ -85,7 +85,7 @@ jobs:
             org.opencontainers.image.vendor=ConduitIO
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@v6.14.0
+        uses: docker/build-push-action@v6.15.0
         with:
           context: .
           push: true