Furo 2025.9.25 incompatible with Sphinx 9.0.0

[kdeldycke]

Sphinx 9.0.0 has just been released, and Furo 2025.9.25 explicitly cap Sphinx dependency to sphinx >= 6.0,<9.0.

So here is the conflicting version resolution happening:

  × No solution found when resolving dependencies:
  ╰─▶ Because only furo<=2025.9.25 is available and furo==2025.9.25 depends on sphinx>=6.0,<9.0, we can conclude that furo>=2025.9.25 depends on sphinx>=6.0,<9.0.

      hint: `furo` was requested with a pre-release marker (e.g., furo>2025.9.25,<2025.10.dev0), but pre-releases weren't enabled (try: `--prerelease=allow`)

[kasium]

PR: #914

[pradyunsg]

https://pypi.org/project/furo/2025.12.19/ is up with Sphinx 9 support!