Bump mocha from 6.1.2 to 6.1.3

Bumps [mocha](https://github.com/mochajs/mocha) from 6.1.2 to 6.1.3.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mochajs/mocha/compare/v6.1.2...v6.1.3

)

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