Setuptools requirement in pyproject.toml seems unnecessary

I maintain the [restrictedpython AUR package](https://aur.archlinux.org/packages/python-restrictedpython), and the Arch Linux setuptools package is currently version 75, which was causing the RestrictedPython build to fail (depending on older versions is possible, but not very simple). https://github.com/zopefoundation/RestrictedPython/blob/07950f933194c0bb96fb6c48b023a4ba195eb60d/pyproject.toml#L6 However RestrictedPython seems to install and function without issues after bypassing the <74 requirement in pyproject.toml (https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=python-restrictedpython#n25). I don't know why that requirement was in place (I quickly looked at the setuptools changelog and it didn't seem to have anything relevant), but it would be great if you could remove it one way or another. Thanks.