fix: docutils<0.21; unpin sphinx-autoapi

[ns-rse]

Questing to solve the issues with pages failing to build I'm trying removing the sphinx-autoapi pinned version and at the same time ensuring docutils<0.21 are installed as part of the docs dependencies. :crossed_fingers:

[SylviaWhittle]

You branched off of main but despite that the tests fail, which is really confusing. I am struggling to read the diff clearly in the GitHub view so can't tell exactly what the differences are.

[SylviaWhittle]

In yet more confusion, I checked out this branch and ran the offending test on python 3.9 on my windows install and it passes??

(apologies for photo of a screen, I don't have a convenient way to transfer stuff from windows to macOS since it's so rare that I need to)

[ns-rse]

I am struggling to read the diff clearly in the GitHub view so can't tell exactly what the differences are.

The test returned an Empty DataFrame when it should have had three rows of statistics.

<aside> Emacs Diff-mode helps (although requires a small amount of editing to remove some of the GitHub additional text). Although in essence all it is doing here is colouring the current (lines that begin with -) and expected (lines that begin with +), for once a screen shot from me...

</aside>

[ns-rse]

Test passed on re-run, closing though as I've solved this locally (and checked the pages build correctly locally) and made a separate PR #961.