GH-125722: Increase minimum supported Sphinx to 8.2.0

[AA-Turner]

Required for #130376, though I don't know how long is prudent to wait following release to increase the minimum requirement.

A

• Issue: Use the latest Sphinx version #125722

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📚 Documentation preview 📚: https://cpython-previews--130444.org.readthedocs.build/

[vstinner]

cc @befeleme FYI

[befeleme]

Is this change intended only for main/3.14?
In Fedora, we're currently at Sphinx 8.1.3. I could test the 8.2.1 and bring back info whether we're ready for this coming in the next alpha (I see there are two breaking changes comparing to 8.1.x). In general, we tend to wait ~month with Sphinx releases, because of the rest of the docs ecosystem which moves significantly slower.

[AA-Turner]

We'll backport it to 3.13 and 3.12 when merged. See the linked issue (#125722) for context and background of why we've changed this policy. Specifically, I took Miro Hrončok's comment in #125722 (comment) as feedback from Fedora.

A

[befeleme]

I read the linked discussion and see the reasoning. Given the question is when rather than whether, for the developmental version of Fedora we may be able to build the docs coming in the next Pythons releases.

[miss-islington-app]

Thanks @AA-Turner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13.
🐍🍒⛏🤖

[bedevere-app]

GH-130858 is a backport of this pull request to the 3.13 branch.

[bedevere-app]

GH-130859 is a backport of this pull request to the 3.12 branch.