feat: upgrade xinference to 0.2.1 which support stream response (#977)

api/requirements.txt

@@ -49,4 +49,4 @@ huggingface_hub~=0.16.4
 transformers~=4.31.0
 stripe~=5.5.0
 pandas==1.5.3
-xinference==0.2.0
+xinference==0.2.1