Fix errors detected by Ruff (#3918)

### What problem does this PR solve?

Fix errors detected by Ruff

### Type of change

- [x] Refactoring

api/apps/conversation_app.py

@@ -281,10 +281,12 @@ def thumbup():
         if req["message_id"] == msg.get("id", "") and msg.get("role", "") == "assistant":
             if up_down:
                 msg["thumbup"] = True
-                if "feedback" in msg: del msg["feedback"]
+                if "feedback" in msg:
+                    del msg["feedback"]
             else:
                 msg["thumbup"] = False
-                if feedback: msg["feedback"] = feedback
+                if feedback:
+                    msg["feedback"] = feedback
             break
 
     ConversationService.update_by_id(conv["id"], conv)