Bump supertest and @types/supertest in /middleware

Bumps [supertest](https://github.com/ladjs/supertest) and [@types/supertest](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/supertest). These dependencies needed to be updated together.

Updates `supertest` from 6.1.3 to 6.3.4
- [Release notes](https://github.com/ladjs/supertest/releases)
- [Commits](ladjs/supertest@v6.1.3...v6.3.4)

Updates `@types/supertest` from 2.0.11 to 6.0.2
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/supertest)

---
updated-dependencies:
- dependency-name: supertest
  dependency-type: direct:development
  update-type: version-update:semver-minor
- dependency-name: "@types/supertest"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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