fix: requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-STARLETTE-10874054

Author: snyk-bot

requirements.txt

@@ -11,7 +11,7 @@ pytest_html==4.0.0
 requests==2.32.0
 fastapi==0.115.3
 uvicorn==0.27.0
-starlette>=0.40.0,<0.42.0
+starlette>=0.47.2
 httpx==0.25.0
 pydantic>=2
 gunicorn==23.0.0