CoW: disable chained assignment detection for Python 3.14

[jorisvandenbossche]

Summary: this disables all chained assignment warnings in case of Python 3.14+, but afterwards #62070 will enable it again specifically for the chained setitem indexing.

@ngoldbaum I extracted the warning disable parts from #61950. I had removed it from that PR thinking we won't need it because of my follow-up PR #62070, but in the end we still need the disabling for the inplace methods (my PR for now only fixes the indexing cases), and we might also need it if we want to backport the python 3.14 support to 2.3.x

[ngoldbaum]

Thanks for leaving my authorship on one of the commits!

[jorisvandenbossche]

Going to merge this to unblock #62318 and #62070 (and backporting this)

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 2.3.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 e209a35403f8835bbcff97636b83d2fc39b51e68

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #62324: CoW: disable chained assignment detection for Python 3.14'

4. Push to a named branch:

git push YOURFORK 2.3.x:auto-backport-of-pr-62324-on-2.3.x

5. Create a PR against branch 2.3.x, I would have named this PR:

"Backport PR #62324 on branch 2.3.x (CoW: disable chained assignment detection for Python 3.14)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[jorisvandenbossche]

Manual backport -> #62375