Bump validator from 10.11.0 to 13.12.0 in /backend-app (#173)

Bumps [validator](https://github.com/validatorjs/validator.js) from 10.11.0 to 13.12.0.
- [Release notes](https://github.com/validatorjs/validator.js/releases)
- [Changelog](https://github.com/validatorjs/validator.js/blob/master/CHANGELOG.md)
- [Commits](validatorjs/validator.js@10.11.0...13.12.0)

---
updated-dependencies:
- dependency-name: validator
  dependency-type: indirect
...

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