chore(deps): bump ujson from 5.11.0 to 5.12.0 in /backend (baserow#5003)

Bumps [ujson](https://github.com/ultrajson/ultrajson) from 5.11.0 to 5.12.0.
- [Release notes](https://github.com/ultrajson/ultrajson/releases)
- [Commits](ultrajson/ultrajson@5.11.0...5.12.0)

---
updated-dependencies:
- dependency-name: ujson
  dependency-version: 5.12.0
  dependency-type: indirect
...

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Author: dependabot[bot]