chore(deps): update dependency supertest to v4

chore(deps): update dependency supertest to v4

This PR contains the following updates:

| Package | Type | Update | Change | References |
|---|---|---|---|---|
| supertest | devDependencies | major | [`^3.3.0` -> `^4.0.0`](https://diff.intrinsic.com/supertest/3.4.2/4.0.0) | [source](https://togithub.com/visionmedia/supertest) |

---

### Release Notes

<details>
<summary>visionmedia/supertest</summary>

### [`v4.0.0`](https://togithub.com/visionmedia/supertest/releases/v4.0.0)

[Compare Source](https://togithub.com/visionmedia/supertest/compare/v3.4.2...v4.0.0)

-   Merge pull request [#&#8203;539](https://togithub.com/visionmedia/supertest/issues/539) from ozzywalsh/fix-agent-defaults  [`abf6bc3`](https://togithub.com/visionmedia/supertest/commit/abf6bc3)
-   Merge pull request [#&#8203;554](https://togithub.com/visionmedia/supertest/issues/554) from visionmedia/use-trust-localhost  [`5914936`](https://togithub.com/visionmedia/supertest/commit/5914936)

</details>

---

### Renovate configuration

:date: **Schedule**: "after 9am and before 3pm" (UTC).

:vertical_traffic_light: **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

:recycle: **Rebasing**: Whenever PR is stale, or if you modify the PR title to begin with "`rebase!`".

:no_bell: **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- renovate-rebase -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [Renovate Bot](https://togithub.com/marketplace/renovate). View repository job log [here](https://renovatebot.com/dashboard#googleapis/nodejs-scheduler).

#58 automerged by dpebot

scheduler/package.json

@@ -22,6 +22,6 @@
     "chai": "^4.2.0",
     "execa": "^1.0.0",
     "mocha": "^6.0.0",
-    "supertest": "^3.3.0"
+    "supertest": "^4.0.0"
   }
 }