dependency: (deps): bump pydantic-core from 2.14.6 to 2.16.1 in /backend

Bumps [pydantic-core](https://github.com/pydantic/pydantic-core) from 2.14.6 to 2.16.1.
- [Release notes](https://github.com/pydantic/pydantic-core/releases)
- [Commits](pydantic/pydantic-core@v2.14.6...v2.16.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

backend/requirements.txt

@@ -24,7 +24,7 @@ pdfminer.six==20231228
 psycopg2==2.9.9
 pycparser==2.21
 pydantic==2.5.3
-pydantic_core==2.14.6
+pydantic_core==2.16.1
 PyJWT==2.8.0
 PyPDF2==1.26.0
 python-dotenv==1.0.0