Refactor Document API (#2833)

### What problem does this PR solve?

Refactor Document API

### Type of change


- [x] Refactoring

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

sdk/python/ragflow/modules/base.py

@@ -18,8 +18,8 @@ class Base(object):
                     pr[name] = value
         return pr
 
-    def post(self, path, json, stream=False):
-        res = self.rag.post(path, json, stream=stream)
+    def post(self, path, json=None, stream=False, files=None):
+        res = self.rag.post(path, json, stream=stream,files=files)
         return res
 
     def get(self, path, params):