Bump pydantic-core from 2.23.4 to 2.34.1 in /backend

Bumps [pydantic-core](https://github.com/pydantic/pydantic-core) from 2.23.4 to 2.34.1.
- [Release notes](https://github.com/pydantic/pydantic-core/releases)
- [Commits](https://github.com/pydantic/pydantic-core/compare/v2.23.4...v2.34.1)

---
updated-dependencies:
- dependency-name: pydantic-core
  dependency-version: 2.34.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

backend/requirements.txt

@@ -37,7 +37,7 @@ platformdirs==4.3.8
 psutil==7.0.0
 py-serializable==2.0.0
 pydantic==2.9.2
-pydantic_core==2.23.4
+pydantic_core==2.34.1
 Pygments==2.19.1
 pyparsing==3.2.3
 python-dateutil==2.9.0.post0