allow sphinx versions 5.x

[renefritze]

AFAICT there was no real need to limit the sphinx version to <5, right?
In general, wouldn't it also suffice to transitively depend on the sphinx versions via breathe's requirements?

[renefritze]

Some failures indicate that there's a more general problem with the CI setup @svenevs .

[njzjz]

Some failures indicate that there's a more general problem with the CI setup @svenevs .

I fixed the problem in #189.

I also hope this PR can be merged.

[svenevs]

thank you for the contribution and nudges! i cherry picked these into #190 folding into a larger "fix it all" pr. sorry it has taken so long to get any movement here, there's oodles of technical debt

AFAICT there was no real need to limit the sphinx version to <5, right?

that yaml thing was a little confusing, what >=4,<5 was saying was "any 4.x" version, specifically "anything greater than or equal to 4, and less than 5" meaning pip will choose latest sphinx 4.x release

that was primarily there to be testing against the latest version in CI, but of course went stale many moons ago

In general, wouldn't it also suffice to transitively depend on the sphinx versions via breathe's requirements?

yes, that used to be the world order, at some point I think we were having issues with a breathe release or needed to support installing their main branch or something -- I remember it happening, hacking, and planning to undo it. going to do an audit there, plan is in #191