Bump mocha from 8.2.1 to 8.4.0

Bumps [mocha](https://github.com/mochajs/mocha) from 8.2.1 to 8.4.0.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v8.2.1...v8.4.0)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]