build(deps-dev): bump @types/mocha from 5.2.5 to 5.2.7

Bumps [@types/mocha](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/mocha) from 5.2.5 to 5.2.7.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/mocha)

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