Use docker builder prune instead of docker system prune in build-docker-image workflow

.gitea/workflows/build-docker-image.yml

@@ -44,5 +44,6 @@ jobs:
           cache-to:   type=registry,ref=${{ secrets.REGISTRY_URL }}/${{ github.repository_owner }}/${{ env.REPO_NAME_LOWER }}:buildcache,mode=max
           
       - name: Clean up Docker in dind
-        run: docker system prune -af --volumes
+        run: docker builder prune -af
+