Require sphinx>3

[jarrodmillman]

Sphinx 3.0 was released in Apr 5, 2020. Our next scheduled release is for September 2022. Sphinx 3 was the first release to officially support Python 3.7 (the minimum version of Python we officially support).

We currently don't even test with sphinx 3.

I would prefer bumping to sphinx>4.0.2, but I wanted to see what people thought about this first.

[rossbar]

I'm 👍 for dropping support for old sphinx versions. In fact, I'd advocate for dropping all unsupported sphinx versions including 3.X, i.e. make the minimum version sphinx 4. Sphinx itself has already stated that they won't backport any patches to <4, and the recent breakage due to code removal from Jinja2 is a strong motivator to update for any project that is still relying on sphinx<4.

I would advocate for something like:

• Release numpydoc 1.3 with the runtime checks for incompatible sphinx/jinja2 combos (see Runtime verification of sphinx and jinja2 versions #381 & MAINT: Dont import for version #382) relatively soon if possible
• Release a 1.4 (or 2.0 if there are strong feelings about it) that drops support for sphinx <4

[larsoner]

I would prefer bumping to sphinx>4.0.2, but I wanted to see what people thought about this first.

4.0.0 is less just under a year old (released may 9, 2021). Requiring 4.0 seems like a quick turnaround, but given that the Sphinx folks aren't supporting it, I can live with it.

I would advocate for something like:

I like this plan to push out a 1.3 ASAP then in >= 1.4 require 4.0. @jarrodmillman would you be up for making another release for 1.3?

[larsoner]

Thanks @jarrodmillman !