chore(deps): bump prometheus-client in /reference-apps/fastapi

Bumps [prometheus-client](https://github.com/prometheus/client_python) from 0.23.1 to 0.24.0.
- [Release notes](https://github.com/prometheus/client_python/releases)
- [Commits](prometheus/client_python@v0.23.1...v0.24.0)

---
updated-dependencies:
- dependency-name: prometheus-client
  dependency-version: 0.24.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

reference-apps/fastapi/requirements.txt

@@ -27,7 +27,7 @@ aio-pika==9.5.8
 python-json-logger==4.0.0
 
 # Observability
-prometheus-client==0.23.1
+prometheus-client==0.24.0
 
 # Testing
 pytest==9.0.2