update the GenerateChatCompletionForm stream to be defaulted to true.

This defaults the /api/chat/ endpoint to default to streaming being true

backend/open_webui/apps/ollama/main.py

@@ -739,7 +739,7 @@ class GenerateChatCompletionForm(BaseModel):
     format: Optional[str] = None
     options: Optional[dict] = None
     template: Optional[str] = None
-    stream: Optional[bool] = None
+    stream: Optional[bool] = True
     keep_alive: Optional[Union[int, str]] = None