[Merge after v2.11.0 Release] Remove support for Python 3.9

[valeriupredoi]

Description

Closes #2406

AFAIK I removed all references for Python 3.9 - if you know of any others please holler back so I can replace them :beer:

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.62%. Comparing base (f9e6f46) to head (e04d666). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2447 +/- ## ======================================= Coverage 94.62% 94.62% ======================================= Files 247 247 Lines 14057 14057 ======================================= Hits 13301 13301 Misses 756 756 ```

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[bouweandela]

I think we do not need from __future__ import annotations anymore with recent Python versions, would you like to give that a try? i.e. remove it from everywhere and then run the GitHub Actions matrix tests to see if it works?

[bouweandela]

This can also be removed: https://github.com/ESMValGroup/ESMValCore/blob/07ba25c425724e61be1ce109ea98a2d791abb3fa/tests/unit/preprocessor/_regrid_esmpy/test_regrid_esmpy.py#L384-L386

[bouweandela]

This needs an update: https://github.com/ESMValGroup/ESMValCore/blob/af5490f9c0e285f65ab8a213629ada7e903c1e36/setup.cfg#L37-L39

[valeriupredoi]

from future import annotations

you're right! It seems it's not needed anymore (after 3.10+), though I couldn't find an official source (yet my reasearch took no longer than 5 whole minutes :rofl: ), will do it here, and test with 3.10

[valeriupredoi]

tests/unit/preprocessor/_regrid_esmpy/test_regrid_esmpy.py

done in https://github.com/ESMValGroup/ESMValCore/pull/2447/commits/df2aa31b94ce10c0f0adc62d9036f2a567067b67

[valeriupredoi]

This needs an update:

https://github.com/ESMValGroup/ESMValCore/blob/af5490f9c0e285f65ab8a213629ada7e903c1e36/setup.cfg#L37-L39

done in https://github.com/ESMValGroup/ESMValCore/pull/2447/commits/fb2411b50f1b4a28110251db11c97de1cc58391d

[valeriupredoi]

@bouweandela have a look at the flake8 barf now that we've removed from future... - F821 is indeed an undefined name in flake8 error parlance, but it's typing assignment, not variable assignment - any suggestions (before I peasantly put a # noqa there :grin: )? Related issue https://github.com/PyCQA/pyflakes/issues/528 - but it doesn't seem to have a proper resolution

[bouweandela]

I tried to fix the flake8 error (it happens because the class used as a type hint is not yet defined at the point where it is used as a type hint, so in some cases you can just re-order the code and then it works), but then I tried to run the tests and found that we still need the from __future__ import annotations also where we use the bare class name (i.e. without quotes) when the used classes are imported only for type checking. In short, I think we cannot yet get rid of the from __future__ import annotations. Thanks for trying though!

[valeriupredoi]

I tried to fix the flake8 error (it happens because the class used as a type hint is not yet defined at the point where it is used as a type hint, so in some cases you can just re-order the code and then it works), but then I tried to run the tests and found that we still need the from __future__ import annotations also where we use the bare class name (i.e. without quotes) when the used classes are imported only for type checking. In short, I think we cannot yet get rid of the from __future__ import annotations. Thanks for trying though!

cheers for testing, bud! Lemme revert the commit then - easy-peasy :+1:

[valeriupredoi]

OK buds, reverted those two last commites (running GA and removing from future) :beer:

[valeriupredoi]

Yep let's do that, maybe we do a rebuild when ESMValTool has the same package specs? We seeing esmpy>=8.6.0 causing some issues with resolving the env with python 3.12 at the mo at Tool, so we can wait a bit

[valeriupredoi]

I'd argue we should add a label a la "warrants/motivates a rebuild" just as we have "needs new ESMValCore release" in Tool - what do you think, bud?

[valeriupredoi]

also, excuse my verbosity today, what do you think I just remove 3.9 from the GA tests ie https://github.com/ESMValGroup/ESMValCore/actions/runs/9393366881 in a separate PR just so that release folks don't get annoyed when it comes to checking tests for the release?

[bouweandela]

They may want to run the GitHub actions on the v2.11.x branch instead of on main, as it is getting rather behind main and I would not expect the failing Python 3.9 tests on the v2.11.x branch as they were introduced in https://github.com/ESMValGroup/ESMValCore/pull/2445#issuecomment-2145281138, which is not included in v2.11.x.

[valeriupredoi]

sounds like what I'd do too :grin:

[valeriupredoi]

@bouweandela now that @ehogan has released 2.11, would you mind if I merged this, so we get us rid of that dinosaur once and for all? :sauropod:

[valeriupredoi]

:sauropod: just about to be extinct :grin: Many thanks for the review @bouweandela :beer: