Update chokidar to v4

[Fuzzyma]

First things first: I am aware that karma is deprecated but I think this has relevance nonetheless.

Chokidar v4 dropped 11 dependencies and karma still gets a solid 11.6 million downloads per month.
As part of the ecosystem cleanup initiative (https://e18e.dev), we try to modernize the ecosystem by reducing bloat, updating old deps and reducing traffic.
I think even tho karma is eol, updating chokidar is a sensible thing to do. It enables all your users (who stick with it for one or the other reason) to install karma just a bit faster.

I would be happy to create a PR for this change if you are up for it.