Deprecate np for releases

[kvz]

It does not support yarn 4, and has no plans to support it either. Meanwhile, i find 4 is a massive speed boost. It's so fast on subsequent runs that i can now have it run automatically which is a game changer.

We'd need a different convenience script to do releases (or fork np if that's easier idk), and document that in the README.md

For now i reverted yarn from 4 to 1 again