Deprecation warning with Pip 22.3.1

[baolsen]

When doing pip install cron-descriptor the following deprecation warning appears:

DEPRECATION: cron-descriptor is being installed using the legacy 'setup.py install' method, because it does not have a 'pyproject.toml' and the 'wheel' package is not installed. pip 23.1 will enforce this behaviour change. A possible replacement is to enable the '--use-pep517' option. Discussion can be found at pypa/pip#8559