Fix: renrank_model and pdf_parser bugs | Update: session API (#2601)

### What problem does this PR solve?

Fix: renrank_model and pdf_parser bugs | Update: session API
#2575
#2559
### Type of change

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

---------

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

sdk/python/ragflow/modules/assistant.py

@@ -76,7 +76,7 @@ class Assistant(Base):
         raise Exception(res["retmsg"])
 
     def get_session(self, id) -> Session:
-        res = self.get("/session/get", {"id": id})
+        res = self.get("/session/get", {"id": id,"assistant_id":self.id})
         res = res.json()
         if res.get("retmsg") == "success":
             return Session(self.rag, res["data"])