Rebuilding assets for existing sites in Docker after image update

I’ve a custom app running with ERPnext on Docker and I’ve build my images as explained by @revant_one in GitHub - castlecraft/custom_frappe_docker

I’ve added a new Javascript file to my app, but isn’t working because this new JS file wasn’t created in sites/assets folder.

The new JS script is present in my app folder in the container and I did bench migrate in the backend container, but JS asset wasn’t rebuild in site folder.

I saw this thread that tells something about changing a version file, but I couldn’t understand which version file must be changed: