优化代码，提高解耦

02_llm_fundamentals/01_basic_llm_invocation.py

@@ -1,14 +1,8 @@
-import os # 导入环境变量
-from dotenv import load_dotenv
-
-load_dotenv()
-api_key = os.getenv("OPENAI_API_KEY")
-
-
+from config import OPENAI_API_KEY
 from openai import OpenAI
 
 client = OpenAI(
-    api_key=api_key,
+    api_key=OPENAI_API_KEY,
     base_url="https://api.deepseek.com")
 
 response = client.chat.completions.create(