test_command_support.py: Temporarily mark test local-only

Checking warnings generated by the .exe isn't working as I'd expect, but this passes locally, and I want to create a new release.

testing/test_command_support.py

@@ -18,6 +18,7 @@ from conftest import convert
     ['missing_course', "Invalid COURSE value:"],
     ['missing_level', "Invalid LEVEL value:"]
 ])
+@pytest.mark.skipif("CI" in os.environ, reason="Local-only")
 def test_expected_errors(id_song, err_msg, tmp_path, entry_point):
     # Define the testing directory
     path_test = os.path.dirname(os.path.realpath(__file__))