Merge pull request #3875 from open-webui/dependabot/pip/backend/dev/pydantic-2.8.2

chore(deps): bump pydantic from 2.7.1 to 2.8.2 in /backend

backend/requirements.txt

 fastapi==0.111.0
 uvicorn[standard]==0.22.0
-pydantic==2.7.1
+pydantic==2.8.2
 python-multipart==0.0.9
 
 Flask==3.0.3