Outdated version of Yargs - dependency vulnerability

[oguilleux]

Hello,

You seem to be using an outdated version of Yargs (8.0.1 - latest : 15.3.1) in which there is dependency called mem which has a vulnerability :

Denial of Service : https://npmjs.com/advisories/1084
I'm using gulp-purifycss and here is the path : gulp-purifycss > purify-css > yargs > os-locale > mem

The latest version of Yargs doesn't seem to be using os-locale.

Thanks for your great work !