Fix issues in API (#3008)

### What problem does this PR solve?

Fix 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/document.py

@@ -70,7 +70,7 @@ class Document(Base):
             return Chunk(self.rag,res["data"].get("chunk"))
         raise Exception(res.get("message"))
 
-    def delete_chunks(self,ids:List[str]):
+    def delete_chunks(self,ids:List[str] = None):
         res = self.rm(f"dataset/{self.dataset_id}/document/{self.id}/chunk",{"ids":ids})
         res = res.json()
         if res.get("code")!=0: