Stop importing cockpit's base1/patternfly.css

This is deprecated API and will be dropped at some point, in favor of projects shipping their own CSS. Please see the deprecation announcement for details.

It seems that this project is only using PatternFly 4, so you can use the same approach as current starter-kit. In recent starter-kit we also fixed/improved a bunch of other build system issues, so maybe this is even a good opportunity to merge the whole starter-kit master branch again?

Please let us know if you run into trouble. Thanks!