MAINT: Test old and new Sphinx versions

[larsoner]

This is a proposal-by-PR:

1. Test the oldest supported sphinx in tests (I don't think it's being done currently?)
2. Test the latest sphinx dev version (should help catch stuff like Incompatibility with Sphinx dev #1404)
3. Refactor test install step into a script (DRY)

No idea if this has been discussed so far but it seemed quick enough to just do it and see what people thought :)

FYI we use a dev test against NumPy/SciPy/matplotlib etc. in MNE-Python and find bugs in their dev branches fairly frequently. As a maintainer it's easy enough to know when a dev failure can be safely ignored for the time being...

[larsoner]

Looks like it's already showing a problem with the pyproject.toml / minimum reqs, assuming I'm interpreting correctly that sphinx==4.2 is meant to be the minimum required version:

ERROR: Cannot install pydata-sphinx-theme, pydata-sphinx-theme[doc]==0.13.4.dev0 and sphinx==4.2 because these package versions have conflicting dependencies.

The conflict is caused by:
    The user requested sphinx==4.2
    pydata-sphinx-theme[doc] 0.13.4.dev0 depends on sphinx>=4.2
    ablog 0.11.0rc2 depends on sphinx>=5.0.0

I'll bump the minimum to 5.0 in this PR but someone should make sure that's the right thing to do!

[larsoner]

... I guess it's just a min required for the doc run, so I'll revert that part. But it means the doc run will never test the oldest sphinx version (maybe okay?)

[larsoner]

... also added concurrency to the GitHub actions build so that pushing repeated commits (like I did here) cancels previous ones in the same PR

[drammock]

thank you @larsoner this was on my mental TODO list (I hadn't managed to even open an issue about it yet)

[larsoner]

Also can't test the doc build job on sphinx dev because of some dependency problem. Something to look at in the future since catching Sphinx warnings early (as it says are checked in this job) is pretty important I think

[drammock]

argh. yes, definitely want to test against sphinx dev; the events of this week make it obvious that we should have been doing that all along.

[drammock]

I'll bump the minimum to 5.0 in this PR but someone should make sure that's the right thing to do!

our policy is to support 2 versions back so dropping 4.x support is correct here.

[drammock]

note to self: the sphinx dev dependency clash is coming from myst-nb which requires sphinx < 6

[larsoner]

note to self: the sphinx dev dependency clash is coming from myst-nb which requires sphinx < 6

@choldgraf looks like the last release was in April, might be time for another that doesn't pin to an ancient Sphinx version :)

[larsoner]

Legit failure! https://github.com/pydata/pydata-sphinx-theme/actions/runs/5893186049/job/15984213602?pr=1413

Looks like it's due to jdillard/sphinx-sitemap#69 . That repo hasn't been updated in 6 months, can we drop sphinx-sitemap?

[larsoner]

All green other than macos taking ages to start. Old (now 5.0) and dev versions now tested in both pytest and doc-build jobs (when using the branch from jdillard/sphinx-sitemap#70 which seems okay until they cut a new version), ready for review/merge from my end

[drammock]

not exactly how I would have done it, but still a big step forward and we can always tweak it later. Thanks @larsoner!!