fix os.cpus is not a function

[superlbr]

as mentioned in #150

[johnnyreilly]

Great! Do you want to update the package.json and changelog.md as well please?

[superlbr]

after yarn outdated, packages need upgrade

@types/node
@types/resolve
chai
css-loader
mocha
mock-require
sinon
ts-loader

[johnnyreilly]

after yarn outdated, packages need upgrade

Don't worry - we'll handle that later

[johnnyreilly]

I'm really sorry but for some reason the CI refuses to trigger and GitHub won't let me merge (not even manually). Could you try resubmitting this change please? I figure that should work okay.

[johnnyreilly]

Unblocked and merged. Thanks!