增加HF_ENDPOINT，避免Connection aborted.

code/chapter3/Qwen.py

@@ -1,3 +1,7 @@
+# 增加HF_ENDPOINT，避免Connection aborted. 
+import os
+os.environ["HF_ENDPOINT"] = "https://hf-mirror.com"
+
 import torch
 from transformers import AutoModelForCausalLM, AutoTokenizer