Bump mocha from 7.0.1 to 8.1.3

Bumps [mocha](https://github.com/mochajs/mocha) from 7.0.1 to 8.1.3.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v7.0.1...v8.1.3)

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

Author: dependabot[bot]