sage-doc silently fails to build properly with recent furo (2023.8.19)

[kiwifb]

Environment

- Gentoo
- sage-on-gentoo built 10.2.beta2 but probably all versions using system furo 2023.8.19 + affected.

Steps To Reproduce

It is normal sage-on-gentoo build using all system components. During the build of documentation I have numerous message

This documentation is not using `furo.css` as the stylesheet. If you have set `html_style` in your conf.py file, remove it.

While the documentation seems to install correctly I have nothing apart from index html pages. All html pages with actual documentations are missing.

Config log

Not relevant as configure is not run in such build.

Package logs

No response

Additional Information

No response

Checklist

• I have searched the existing issues for a bug report that matches the one I want to file, without success.
• I have read the documentation and troubleshoot guide

[kiwifb]

As it turns out furo-2023.8.19 has compatibility problems with some versions of sphinx. Version to avoid, 2023.9.10 works well.
pradyunsg/furo@9e40071

[dimpase]

the up to date furo works great with sphinx 7.2.6 (with #36296). And Sage's furo doesn't work with the up to date sphinx.

It's high time we upgrade our sphinx, furo, etc...

Can this one be closed?

[kiwifb]

Yes. If we have all that coming and know what to avoid it is all good.