Installation warning with pip v23

[dkirkham]

When installing wagtail-django-recaptcha with pip v23, the following warning is issued:

DEPRECATION: wagtail-django-recaptcha 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

Environment: Python 3.8, pip v23.0.1 with venv

Pip v23.1 is scheduled for April 2023.

[zerolab]

This now fails with recent versions of pip and poetry