grunt-lib-phantomjs is unmaintained

[ossdev07]

Feature Request
PhantomJS is an unmaintained project, and grunt-lib-phantomjs is using it also it is unmaintained and it will be good to replace it with some maintained alternatives.

Solution
I would like to ask the team if they will be interested in dropping phantomjs as browser testing dependency.

Alternatives to be considered
chrome headless could be the best alternative to use in replacement to phantomjs.

It will be a delight to see phantomjs removed from the package, Please suggest what it would take to drop the grunt-lib-phantomjs dependency and add support for chrome headless also I have found one package grunt-lib-puppeteer-istanbul which could be used as an alternative to it.