Bump pydantic from 2.5.3 to 2.6.1 in /backend

Bumps [pydantic](https://github.com/pydantic/pydantic) from 2.5.3 to 2.6.1.
- [Release notes](https://github.com/pydantic/pydantic/releases)
- [Changelog](https://github.com/pydantic/pydantic/blob/main/HISTORY.md)
- [Commits](pydantic/pydantic@v2.5.3...v2.6.1)

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

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

Author: dependabot[bot]

backend/requirements-docker.txt

@@ -3,7 +3,7 @@ asyncio==3.4.3
 asyncpg==0.29.0
 fastapi==0.109.1
 httpx==0.26.0
-pydantic==2.5.3
+pydantic==2.6.1
 python-multipart==0.0.7
 python-jose==3.3.0
 uvicorn==0.25.0

backend/src/requirements_docker.txt

@@ -2,7 +2,7 @@ ariadne==0.21
 fastapi==0.109.1
 httpx==0.26.0
 psycopg2-binary==2.9.9
-pydantic==2.5.3
+pydantic==2.6.1
 python-multipart==0.0.7
 python-jose==3.3.0
 SQLAlchemy==2.0.24