build(deps-dev): bump uglify-js from 3.7.3 to 3.9.4
build(deps-dev): bump uglify-js from 3.7.3 to 3.9.4

Bumps [uglify-js](https://github.com/mishoo/UglifyJS) from 3.7.3 to 3.9.4.
- [Release notes](https://github.com/mishoo/UglifyJS/releases)
- [Commits](https://github.com/mishoo/UglifyJS/compare/v3.7.3...v3.9.4)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
mostjs/hold,mostjs/hold