Remove upperbound on sphinx

[jarrodmillman]

See #660.

[choldgraf]

Hmmm - I am not inherently opposed to removing the upper bound, though I think the reason we were using it in the first place is that Sphinx tends to fairly often introduce breaking changes in its major releases (anecdotally much more often than most packages). So I worry that telling people "the theme supports any latest version of Sphinx" without actually testing that this is true for the next major version, will confuse people when things break

I'm curious how numpy handles this kind of thing? Does it have "canary" CI/CD jobs that run pre-release versions of major dependencies, will not block PRs?

[choldgraf]

What do you or others think about:

• removing the hard version pin
• noting in the docs the versions of sphinx that are supported and explicitly saying "no promises" for any other versions
• adding a GitHub action that runs on CRON weekly against the main branch of sphinx?

[choldgraf]

Note: I am also fine just removing the upper pin in general, if we also:

• Document clearly in these docs that we don't promise support for the latest version of Sphinx.
• Open an issue to track adding a GitHub Actions job for testing on latest w/ Sphinx

Any objections to that?

[jarrodmillman]

Open an issue to track adding a GitHub Actions job for testing on latest w/ Sphinx

Currently, we test

  tests:
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest]
        python-version: [3.7, 3.8, 3.9, "3.10"]
        # Manually specify one OSX + Windows build to make sure it works there.
        include:
          - python-version: "3.10"
            dev: true

prereleases of sphinx and jinja2

      - name: Install pre-release dependencies
        if: ${{ matrix.dev }}
        run: pip install --upgrade --pre sphinx jinja2

on Python 3.10. @choldgraf This seems sufficient to me. Sphinx 1, 2, 3, 4, and 5 all had prereleases.

[jarrodmillman]

LGTM. Thanks @choldgraf!

[choldgraf]

I just updated this one a little bit and added extra information about a rough policy for Sphinx, I hope that's OK with you @jarrodmillman !