Use npm v7 to allow audit fix work

This is related to https://github.com/adjust/cordova_sdk/issues/73 and it's fixed.

We should update cordova-fetch: https://cordova.apache.org/announcements/2021/02/02/cordova-fetch-3.0.1.html

{{npm uninstall -g cordova
npm install -g cordova}}

And then run audit fix