Add hf_token and use as arg to instantiate model

app.py

@@ -9,7 +9,9 @@ from smolagents import CodeAgent, HfApiModel
 # --- Constants ---
 DEFAULT_API_URL = "https://agents-course-unit4-scoring.hf.space"
 
-model = HfApiModel()
+HF_TOKEN = os.getenv("HF_TOKEN")
+model = HfApiModel(api_key=HF_TOKEN)
+
 
 tools = []