chore(dependencies): Bump uglifier from 3.2.0 to 4.0.1
chore(dependencies): Bump uglifier from 3.2.0 to 4.0.1

Bumps [uglifier](https://github.com/lautis/uglifier) from 3.2.0 to 4.0.1.
- [Changelog](https://github.com/lautis/uglifier/blob/master/CHANGELOG.md)
- [Commits](https://github.com/lautis/uglifier/compare/v3.2.0...v4.0.1)
alphagov/frontend,alphagov/frontend,alphagov/frontend,alphagov/frontend