feat: change whitelistPatterns to safelist
feat: change whitelistPatterns to safelist

The options naming for this packages has changed https://github.com/FullHuman/purgecss/tree/master/packages/postcss-purgecss
it no longer accepts `whitelistPatterns` key but accepts `safelist` instead.

I spent some time debugging an issue with styles not being shipped with prod environment, maybe this change will help someone avoid that :D
salsify/ember-css-modules,salsify/ember-css-modules