Update jest to latest version
Update jest to latest version

I was getting weird line numbers back from eslint. I thought I could fix
that by upgrading, but it made no difference. Still, being on a recent
version makes sense.

I suspect the line number issue is coming from the fact that we use
flow.

Galooshi/import-js,trotzig/import-js,trotzig/import-js,trotzig/import-js