Bump minimist, gulp-clean and mocha (prebid#9111)

Bumps [minimist](https://github.com/minimistjs/minimist) to 1.2.6 and updates ancestor dependencies [minimist](https://github.com/minimistjs/minimist), [gulp-clean](https://github.com/peter-vilja/gulp-clean) and [mocha](https://github.com/mochajs/mocha). These dependencies need to be updated together.


Updates `minimist` from 0.0.8 to 1.2.6
- [Release notes](https://github.com/minimistjs/minimist/releases)
- [Changelog](https://github.com/minimistjs/minimist/blob/main/CHANGELOG.md)
- [Commits](minimistjs/minimist@v0.0.8...v1.2.6)

Updates `gulp-clean` from 0.3.2 to 0.4.0
- [Release notes](https://github.com/peter-vilja/gulp-clean/releases)
- [Commits](peter-vilja/gulp-clean@v0.3.2...v0.4.0)

Updates `mocha` from 5.2.0 to 10.0.0
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v5.2.0...v10.0.0)

---
updated-dependencies:
- dependency-name: minimist
  dependency-type: indirect
- dependency-name: gulp-clean
  dependency-type: direct:development
- dependency-name: mocha
  dependency-type: direct:development
...

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