Bump qs from 6.5.2 to 6.5.3 in /backend

Bumps [qs](https://github.com/ljharb/qs) from 6.5.2 to 6.5.3.
- [Release notes](https://github.com/ljharb/qs/releases)
- [Changelog](https://github.com/ljharb/qs/blob/main/CHANGELOG.md)
- [Commits](ljharb/qs@v6.5.2...v6.5.3)

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

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Author: dependabot[bot]