Update docker/build-push-action action to v6

Author: renovate[bot]

.github/workflows/ghcr.yml

@@ -32,7 +32,7 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Build and push
-        uses: docker/build-push-action@v5.4.0
+        uses: docker/build-push-action@v6.9.0
         with:
           context: .
           push: true