Why Node 10 when kuma uses Node 12?

[peterbe]

This project's Dockerfile uses Node 10
but in Kuma we're using Node 12

Perhaps I'll never understand how kuma and kumascript connect and relate in terms of docker and releases but shouldn't it make sense to CI Kumascript with the same version of Node as what we're going to be using in Kuma? @escattone

Also, Node 10 is not the current LTS version.