chore(deps): update pydantic requirement in /server/ai-gateway

Updates the requirements on [pydantic](https://github.com/pydantic/pydantic) to permit the latest version.
- [Release notes](https://github.com/pydantic/pydantic/releases)
- [Changelog](https://github.com/pydantic/pydantic/blob/main/HISTORY.md)
- [Commits](pydantic/pydantic@v2.0...v2.13.4)

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

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

Author: dependabot[bot]

server/ai-gateway/requirements.txt

@@ -2,7 +2,7 @@ fastapi>=0.115.0
 uvicorn[standard]>=0.30.0
 gunicorn>=22.0.0
 openai>=1.50.0
-pydantic>=2.0.0
+pydantic>=2.13.4
 redis>=5.0.0
 python-jose[cryptography]>=3.3.0
 httpx>=0.27.0