Update docker/build-push-action action to v6.15.0 (#440)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/docker.yml

@@ -40,7 +40,7 @@ jobs:
             type=edge,branch=$repo.default_branch
 
       - name: build+push
-        uses: docker/build-push-action@0adf9959216b96bec444f325f1e493d4aa344497 # v6.14.0
+        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6.15.0
         with:
           platforms: linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64
           push: ${{ github.ref == 'refs/heads/master' }}