chore(deps): update fastapi requirement in /api-server

Updates the requirements on [fastapi](https://github.com/fastapi/fastapi) to permit the latest version.
- [Release notes](https://github.com/fastapi/fastapi/releases)
- [Commits](fastapi/fastapi@0.139.0...0.139.2)

---
updated-dependencies:
- dependency-name: fastapi
  dependency-version: 0.139.2
  dependency-type: direct:production
...

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

Author: dependabot[bot]

api-server/requirements.txt

@@ -1,4 +1,4 @@
-fastapi>=0.139.0
+fastapi>=0.139.2
 uvicorn[standard]>=0.51.0
 httpx>=0.28.1
 pydantic>=2.13.4