pip install reports warning for upcoming pip 23.1

[jliu70]

When I ran pip install circup, I saw the following WARNING message:

DEPRECATION: circup 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

Just wanted to bring this to the attention of the maintainers.

[tekktrik]

It's probably worth solving this by switching to pyproject.toml. A quick look at setup.py doesn't actually reveal any runtime logic that can't be implemented that way.