Add preliminary support for Python 3.14

[icemac]

Problems:

• z3c.pt using no longer existing ast.Str – Configuring for pure-python z3c.pt#32
• zope.pagetemplate using no longer existing ast.Str it is not used there at all
• Zope itself uses no longer existing ast.Str
• Tests break because ast.Str is still used – chameleon 4.4.4 seems to be the reason
• Tests on Windows fail

Other compatibility issues that may cause problems are captured in #1259.

[icemac]

I have no idea where this ast.Str comes from: I searched zopefoundation and Chameleon 4.4.4 which is still used – no success.

So I am giving up here now. Anyone to take over?

[dataflake]

ast.Str comes from Chameleon 4.4.4. The references were fixed in version 4.6.0. We cannot move to that version until malthe/chameleon#438 is fixed - unfortunately I have not gotten any response at all.

[dataflake]

So the major issue for Python 3.14 support is now lack of support for Chameleon >= 4.5.0. See #1252 and malthe/chameleon#438, which is receiving ZERO attention.

It used to be @d-maurer who took on those page template-related issues but he's fallen completely silent. I hope he is alright.

[dataflake]

After Chameleon has been fixed there's just one odd test-related issue on Windows. The wsgischema.xml file in Zope2/Startup/ cannot be found anymore.

[davisagli]

It looks maybe related to changes in urllib: https://docs.python.org/3/whatsnew/3.14.html#urllib

[dataflake]

The Windows/Python 3.14 issue is coming out of ZConfig and as @davisagli suspects due to changes in urllib. I don't have a Windows system set up so I can't test any of this locally. I have a branch in ZConfig at https://github.com/zopefoundation/ZConfig/tree/config-with-pure-python-template-9fcd3d67 where I already fixed some other tests, ZConfig never got tested on Windows at all. I am not sure right now how to proceed because I don't know how ZConfig could produce better or correct file paths on Windows. They look perfectly fine to me.

[dataflake]

This is now done, all remaining work for a Python 3.14-compatible release continues in other tasks like #1259.