chore(deps): update dependency supertest to v3

[renovate[bot]]

This Pull Request updates dependency supertest from ^2.0.0 to ^3.0.0

Release Notes

### [`v3.1.0`](https://github.com/visionmedia/supertest/blob/master/CHANGELOG.md#​310--2018-04-24) [Compare Source](https://github.com/visionmedia/supertest/compare/v3.0.0...v3.1.0) =================== * PR-473 - Remove unused dependency in Readme (thanks @​pedro-otero) * PR-472 - Update travis node versions (thanks @​rimiti) * PR-470 - Upgrade the superagent node module to resolve security vulnerabilities & fix the __proto__ property deprecation (thanks @​levioza) * PR-446 - Fix bug, always pass on errors if no response (thanks @​bkeepers) * PR-418 - Add post() examples to the README (thanks @​kevinburke) * PR-297 - Add a .host() method to set a host other than 127.0.0.1 (thanks @​mikec) * PR-275 - Removed ambiguously misappropriated cultural references from readme (thanks @​reallistic) --- ### [`v3.0.0`](https://github.com/visionmedia/supertest/blob/master/CHANGELOG.md#​300--2017-01-29) [Compare Source](https://github.com/visionmedia/supertest/compare/5930d2cee1191de782d4e0b50629c5debe1b0aab...v3.0.0) =================== * PR-373 - Allow TestAgent pass a cert and key to request (thanks @​toefraz) * PR-392 - Update readme with promise example (thanks @​ajouve) * PR-400 - Update to superagent 3 (thanks @​alphashuro) ---

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