DEP: update minimal recommendation for matplotlib (3.3.4 -> 3.6.0) - #16557

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@eerovaher reminded me that image tests were still somehow setup to use mpl 3.3.4 so I'm going to update that too.

FYI @Cadair

switching to draft for now, until I know for sure that CI stays green.

of course one blocker for such PR is that the circleci job named mpl334 is currently required for merging

1. In PR like this, I can override the branch protection checks because I will have to update the rules after merge, so don't sweat about mpl334 missing. :)
2. Should we delete py310-test-image-mpl334-cov.json?
3. By SPEC 0, should we bump straight to matplotlib 3.6? 🤔

SPEC 0 says bump to 3.6.0 in Q3 2024 which would be our next release right? So yeah I think we should bump to 3.6.0 now.

Should we delete py310-test-image-mpl334-cov.json?

Yes

If we need to bump to 3.6.0 now we should rename the mpl350 JSON file to mpl360, add a mpl360 job and see if any of the hashes need to be updated.

By popular demand, now bumping to 3.6.0 !

LGTM but needs a change log. Thanks!

done !

Updated the branch protection rules. This means all open PRs will need a rebase. FYI.

Thanks!