Nodejs version in node-RED docker container

Hi there, I've written a little Node-Red project, that relies on the docker container of Node-Red. I would like to upgrade to a newer nodejs version. Currently I'm using nodejs version 10 (slim). How can I update to the active nodejs LTS version 14? https://nodered.org/docs/faq/node-versions says it is supported, but I could find a container tag for it.