Add validator to check compat between Plone and Python version

[davisagli]

Fixes #54

[stevepiercy]

Plone 6.0 Python support shifted both its min and max versions up.

[davisagli]

Plone 6.0 Python support shifted both its min and max versions up.

@stevepiercy Where? I thought I remembered that, but the 6.0.x branch of CMFPlone still includes support for Python 3.8 and not 3.13: https://github.com/plone/Products.CMFPlone/blob/6.0.x/setup.py#L24

Maybe @mauritsvanrees can remind me...

[stevepiercy]

@davisagli https://plone.org/download/release-schedule

[stevepiercy]

Also https://community.plone.org/t/plone-6-1-0b2-released/20285

[davisagli]

@stevepiercy @ericof Updated to match the actual release policy. I also removed 3.9 because cookieplone itself already doesn't support it (for some time). Which means the supported versions are now the same between Plone 6.0 and Plone 6.1, and I don't need to add the additional complexity of the new validator.

[stevepiercy]

Wait, Cookieplone does not support Python 3.9? I did not know that, but looking at the blame for pyproject.toml, I see it never did. That means we have some more minor changes to make. We'll also need to update documentation for the Cookieplone installation.

But first, does Cookieplone still support Plone 6.0?

1. We need to update pyproject.toml by adding 3.13 to the trove classifier and https://github.com/plone/cookieplone/blame/main/pyproject.toml#L82. Also maybe change its status from alpha while we're at it?
2. In documentation, we state Python requirements for Plone 6.1, but not 6.0. We should state which versions of Plone are supported by Cookieplone.
3. Plone 6.0 supports Python 3.9, but Cookieplone does not, so we'll need to make a note for anyone who wants to use Python 3.9 for Cookieplone that it is just not possible. Instead they must use the deprecated cookiecutter-plone-starter install method.

@davisagli @mauritsvanrees @ericof does all that sound right? Any other changes needed?

[davisagli]

@stevepiercy

But first, does Cookieplone still support Plone 6.0?

Yes, and it still generates a project with the latest Plone 6.0 by default unless you say Yes for prerelease versions, since we don't have a final release of Plone 6.1 yet.

We need to update pyproject.toml by adding 3.13 to the trove classifier and https://github.com/plone/cookieplone/blame/main/pyproject.toml#L82. Also maybe change its status from alpha while we're at it?

Right, I missed this in my previous PR. Done in #56

In documentation, we state Python requirements for Plone 6.1, but not 6.0. We should state which versions of Plone are supported by Cookieplone.

Cookieplone can generate a backend for either Plone 6.0 or 6.1.

Plone 6.0 supports Python 3.9, but Cookieplone does not, so we'll need to make a note for anyone who wants to use Python 3.9 for Cookieplone that it is just not possible. Instead they must use the deprecated cookiecutter-plone-starter install method.

I would discourage anyone from starting a new project using such an old Python. Security support for Python 3.9 ends in October 2025.

[stevepiercy]

Thanks! PR created: plone/documentation#1834