Bumps [gulp-changed](https://github.com/sindresorhus/gulp-changed) from 3.2.0 to 4.0.0.
- [Release notes](https://github.com/sindresorhus/gulp-changed/releases)
- [Commits](https://github.com/sindresorhus/gulp-changed/compare/v3.2.0...v4.0.0)