⬆ Bump pydantic-settings from 2.11.0 to 2.12.0 in /backend (#2000)

Bumps [pydantic-settings](https://github.com/pydantic/pydantic-settings) from 2.11.0 to 2.12.0.
- [Release notes](https://github.com/pydantic/pydantic-settings/releases)
- [Commits](pydantic/pydantic-settings@v2.11.0...v2.12.0)

---
updated-dependencies:
- dependency-name: pydantic-settings
  dependency-version: 2.12.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]