Bump diff and grunt-contrib-nodeunit

Bumps [diff](https://github.com/kpdecker/jsdiff) to 4.0.2 and updates ancestor dependency [grunt-contrib-nodeunit](https://github.com/gruntjs/grunt-contrib-nodeunit). These dependencies need to be updated together.


Updates `diff` from 1.4.0 to 4.0.2
- [Release notes](https://github.com/kpdecker/jsdiff/releases)
- [Changelog](https://github.com/kpdecker/jsdiff/blob/master/release-notes.md)
- [Commits](kpdecker/jsdiff@v1.4.0...v4.0.2)

Updates `grunt-contrib-nodeunit` from 2.1.0 to 5.0.0
- [Release notes](https://github.com/gruntjs/grunt-contrib-nodeunit/releases)
- [Changelog](https://github.com/gruntjs/grunt-contrib-nodeunit/blob/main/CHANGELOG)
- [Commits](gruntjs/grunt-contrib-nodeunit@v2.1.0...v5.0.0)

---
updated-dependencies:
- dependency-name: diff
  dependency-type: indirect
- dependency-name: grunt-contrib-nodeunit
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>