Bump supertest from 6.2.3 to 6.2.4 (#278)

Bumps [supertest](https://github.com/visionmedia/supertest) from 6.2.3 to 6.2.4.
- [Release notes](https://github.com/visionmedia/supertest/releases)
- [Commits](forwardemail/supertest@v6.2.3...v6.2.4)

---
updated-dependencies:
- dependency-name: supertest
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Merlijn Vos <[email protected]>

Author: dependabot[bot]