fix: fix return value

tests/test_requirements_detection.py

@@ -21,7 +21,7 @@ class TestWebScrapingAndReporting(unittest.TestCase):
     def test_fetch_html_failure(self):
         """测试fetch_html在请求失败时返回None。"""
         with patch("requests.get") as mocked_get:
-            mocked_get.return_code.status_code = 404
+            mocked_get.return_value.status_code = 404
             url = "http://example.com"
             result = fetch_html(url)
             self.assertIsNone(result)