CLI utilities tests fail on macOS

[da4089]

Quick Summary
The two CLI utilities test cases fail when running on macOS.

Context

• vObject version: master
• Python version: 3.9
• Operating system and version: macOS "Big Sur" 11.7.10

Description

====================================================================================================== FAILURES =======================================================================================================
___________________________________________________________________________________________________ test_change_tz ____________________________________________________________________________________________________

    def test_change_tz():
        result = run_cli_tool(Cli.change_tz, ["--version"])
        assert result.returncode == 0

        result = run_cli_tool(Cli.change_tz, [])
>       assert result.returncode == 2
E       assert 0 == 2
E        +  where 0 = CompletedProcess(args=['change_tz'], returncode=0, stdout="error: too few arguments given\nUsage: change_tz [options] ics_file [timezone]\n\nchange_tz will convert the timezones in an ics file.\n\nOptions:\n  --version       show program's version number and exit\n  -h, --help      show this help message and exit\n  -u, --only-utc  Only change UTC events.\n  -l, --list      List available timezones\n\n", stderr='').returncode

tests/test_cli.py:19: AssertionError
____________________________________________________________________________________________________ test_ics_diff ____________________________________________________________________________________________________

    def test_ics_diff():
        result = run_cli_tool(Cli.ics_diff, ["--version"])
        assert result.returncode == 0

        result = run_cli_tool(Cli.ics_diff, [])
>       assert result.returncode == 2
E       assert 0 == 2
E        +  where 0 = CompletedProcess(args=['ics_diff'], returncode=0, stdout="error: too few arguments given\nUsage: ics_diff [options] ics_file1 ics_file2\n\nics_diff will print a comparison of two iCalendar files\n\nOptions:\n  --version             show program's version number and exit\n  -h, --help            show this help message and exit\n  -i, --ignore-dtstamp  ignore DTSTAMP lines [default: False]\n\n", stderr='').returncode

tests/test_cli.py:28: AssertionError
=============================================================================================== short test summary info ===============================================================================================
FAILED tests/test_cli.py::test_change_tz - assert 0 == 2
FAILED tests/test_cli.py::test_ics_diff - assert 0 == 2
============================================================================================ 2 failed, 56 passed in 17.11s ============================================================================================

To Reproduce

pytest -v tests

Further Notes
I haven't investigated this in sufficient detail yet; creating this issue so I don't forget.

[rsb-23]

I think we should add test_os.yml in workflow with base python and all 3 OS to avoid this