chore(deps): update docker/build-push-action action to v6.15.0

Author: renovate[bot]

.github/workflows/deploy-docker-image.yml

@@ -66,7 +66,7 @@ jobs:
       # - 'latest' for successful builds on the main branch.
       # - '<short_branch_name>' pushes to non-main branches.
       - name: Build and push Docker image
-        uses: docker/build-push-action@ca877d9245402d1537745e0e356eab47c3520991 # v6.13.0
+        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6.15.0
         with:
           context: .
           push: true