Bump pydantic from 2.10.4 to 2.13.4 in /backend (#30)

Bumps [pydantic](https://github.com/pydantic/pydantic) from 2.10.4 to 2.13.4.
- [Release notes](https://github.com/pydantic/pydantic/releases)
- [Changelog](https://github.com/pydantic/pydantic/blob/main/HISTORY.md)
- [Commits](pydantic/pydantic@v2.10.4...v2.13.4)

---
updated-dependencies:
- dependency-name: pydantic
  dependency-version: 2.13.4
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: ☣️ Mr. The Plague ☣️ <3779295+DotNetRussell@users.noreply.github.com>

Author: dependabot[bot]

backend/requirements.txt

@@ -1,6 +1,6 @@
 fastapi==0.115.6
 uvicorn[standard]==0.51.0
 httpx==0.28.1
-pydantic==2.10.4
+pydantic==2.13.4
 pydantic-settings==2.14.2
 python-dotenv==1.2.2