Bugfix: Mock persisted beyond intended test case

tests/test_settings_definition.py

@@ -1,5 +1,5 @@
 import os
-from unittest.mock import Mock
+from unittest.mock import patch
 
 from base import BaseTest
 from seedsigner.models.settings_definition import SettingsConstants
@@ -31,8 +31,7 @@ class TestSettingsDefinition(BaseTest):
         # We're going to mock the `root` results to include the absent language code's .mo file
         mocked_results = [(os.path.join(root, "en", "LC_MESSAGES"), [], ["messages.po", "messages.mo"])]
         mocked_results.append((os.path.join(root, absent_language_code, "LC_MESSAGES"), [], ["messages.po", "messages.mo"]))
-        os.walk = Mock(return_value=mocked_results)
-
+        with patch("os.walk", return_value=mocked_results):
             # Recheck w/our mocked dir listing:
             detected_languages = [lang_tuple[0] for lang_tuple in SettingsConstants.get_detected_languages()]
             assert absent_language_code in detected_languages