fix #1507

Former-commit-id: 1ba9c53bd9743fa95fca1516c0ed9da352dbe9a1

src/cli_demo.py

@@ -1,4 +1,5 @@
 from llmtuner import ChatModel
+from llmtuner.extras.misc import torch_gc
 
 try:
     import platform
@@ -27,6 +28,7 @@ def main():
 
         if query.strip() == "clear":
             history = []
+            torch_gc()
             print("History has been removed.")
             continue