Fix some issues in API (#2902)

### What problem does this PR solve?

Fix some issues in API

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>

sdk/python/ragflow/modules/base.py

@@ -22,7 +22,7 @@ class Base(object):
         res = self.rag.post(path, json, stream=stream,files=files)
         return res
 
-    def get(self, path, params):
+    def get(self, path, params=None):
         res = self.rag.get(path, params)
         return res