Fix tests on CI

tests/test_cli.py

@@ -128,6 +128,7 @@ class TestArgumentParsing:
 
         if os.access(nb_path, os.R_OK):  # pragma: no cover
             # doesn't work on CI due to Docker weirdness
+            expected.checked = True
             pytest.skip("failed to make file unreadable")
         else:  # pragma: no cover
             result = runner.run(nb_path)