Update requirements.txt

requirements.txt

@@ -1,6 +1,6 @@
-fastapi==0.103.1
-uvicorn==0.23.2
-openai==1.6.1
-pydantic==2.3.0
-python-dotenv==1.0.0
-gunicorn==21.2.0
+fastapi>=0.95.0
+uvicorn>=0.21.0
+openai>=0.27.0
+python-dotenv>=0.21.0
+pydantic>=1.10.0
+python-multipart>=0.0.5