chore: Update docker/build-push-action action to v6.15.0

Author: grafanarenovatebot[bot]

Diff for: .github/workflows/build_and_publish.yaml

@@ -96,7 +96,7 @@ jobs:
         uses: docker/setup-buildx-action@f7ce87c1d6bead3e36075b2ce75da1f6cc28aaca # v3.9.0
 
       - name: build docker image (no browser)
-        uses: docker/build-push-action@0adf9959216b96bec444f325f1e493d4aa344497 # v6.14.0
+        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6.15.0
         with:
           context: .
           push: false
@@ -107,7 +107,7 @@ jobs:
           cache-to: type=gha,mode=max
 
       - name: build docker image (browser)
-        uses: docker/build-push-action@0adf9959216b96bec444f325f1e493d4aa344497 # v6.14.0
+        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6.15.0
         with:
           context: .
           push: false