[DESKTOP_ENVIRONMENT] Fixes for Python < 3.8 unittest.mock.mock_open

`__iter__` does not consume `read_data` before Python 3.8, causing tests
to fail.

archey/test/entries/test_archey_desktop_environment.py

@@ -125,8 +125,11 @@ def test_environment_detection_4(self, _) -> None:
 """
         ),
     )
-    def test_environment_detection_4_desktop_file(self, _) -> None:
+    def test_environment_detection_4_desktop_file(self, _mock_open) -> None:
         """_environment_detection against legacy `SESSION_DESKTOP` pointing to a desktop file"""
+        # Override `mock_open`'s __iter__ magic method for Python < 3.8
+        _mock_open.__iter__ = iter(_mock_open.read_data.splitlines())
+
         self.assertEqual(
             DesktopEnvironment._environment_detection(),  # pylint: disable=protected-access
             "Retro-Home",