Bump form-data from 4.0.2 to 4.0.4 in /test-apps/express-backend

Bumps [form-data](https://github.com/form-data/form-data) from 4.0.2 to 4.0.4.
- [Release notes](https://github.com/form-data/form-data/releases)
- [Changelog](https://github.com/form-data/form-data/blob/master/CHANGELOG.md)
- [Commits](form-data/form-data@v4.0.2...v4.0.4)

---
updated-dependencies:
- dependency-name: form-data
  dependency-version: 4.0.4
  dependency-type: indirect
...

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

Author: dependabot[bot]