build(deps): bump pydantic-settings from 2.3.4 to 2.6.1 in /api

Bumps [pydantic-settings](https://github.com/pydantic/pydantic-settings) from 2.3.4 to 2.6.1.
- [Release notes](https://github.com/pydantic/pydantic-settings/releases)
- [Commits](pydantic/pydantic-settings@v2.3.4...v2.6.1)

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

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

api/requirements.txt

@@ -1,7 +1,7 @@
 fastapi==0.111.0
 pydantic==2.8.2
 pydantic_core==2.20.1
-pydantic-settings==2.3.4
+pydantic-settings==2.6.1
 uvicorn==0.32.1
 sqlmodel==0.0.19
 databases[mysql]