Help fixing black docs build with furo 2023.8.19

[cooperlees]

Howdy all,

We seem to be running into the following error:

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

• Actions fails I can repro locally: https://github.com/psf/black/actions/runs/5922834942/job/16057411149?pr=3848
• I read Unable to build Furo docs - getting `exception: '_static/styles/furo.css' is not in list` #299

I tried commenting out anything I thought could be causing an issues but can not work out our cause as we don't set html_tyle from what I can see in the black/docs/conf.py. Any thoughts on what's causing this?

[dgw]

See #693, #708, possibly #710

[cooperlees]

Thanks. It was upgrade to sphinx 7.2.3 and fix intersphinx_mapping in the config.