Bump formidable and supertest in /internal-employee-directory/backend

Bumps [formidable](https://github.com/node-formidable/formidable) to 3.5.4 and updates ancestor dependency [supertest](https://github.com/ladjs/supertest). These dependencies need to be updated together.


Updates `formidable` from 2.1.2 to 3.5.4
- [Release notes](https://github.com/node-formidable/formidable/releases)
- [Changelog](https://github.com/node-formidable/formidable/blob/master/CHANGELOG.md)
- [Commits](https://github.com/node-formidable/formidable/commits)

Updates `supertest` from 6.3.4 to 7.1.0
- [Release notes](https://github.com/ladjs/supertest/releases)
- [Commits](forwardemail/supertest@v6.3.4...v7.1.0)

---
updated-dependencies:
- dependency-name: formidable
  dependency-version: 3.5.4
  dependency-type: indirect
- dependency-name: supertest
  dependency-version: 7.1.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]