Support rollup v2

[christophehurpeau]

Hello,
thank you for this module.

This doesnt work with rollup v2:

    Cannot find module 'rollup-pluginutils' from '../../node_modules/rollup-plugin-ignore-import/rollup-plugin-ignore-import.js'

Could you update to make it work ?
Or is there another alternative plugin ?

[ixrock]

@christophehurpeau as workaround just install extra npm package rollup-pluginutils, should work afterwards.
Yarn: yarn add rollup-pluginutils -D
NPM: npm i rollup-pluginutils --save-dev