DOC: fix deprecation warnings in examples

[StefRe]

PR Summary

• The dist attribute was deprecated in Matplotlib 3.6 and will be removed two minor releases later.
• Passing the loc parameter of init() positionally is deprecated since Matplotlib 3.6; the parameter will become keyword-only two minor releases later.
• Passing the radius parameter of init() positionally is deprecated since Matplotlib 3.6; the parameter will become keyword-only two minor releases later.
• Passing the closed parameter of init() positionally is deprecated since Matplotlib 3.6; the parameter will become keyword-only two minor releases later.
• Auto-removal of grids by pcolor() and pcolormesh() is deprecated since 3.5 and will be removed two minor releases later; please call grid(False) first.

(#23855 was for the tutorials, this is for the examples, sorry - I didn't notice it first that there were deprecations in the examples too)

PR Checklist

Tests and Styling

• [N/A] Has pytest style unit tests (and pytest passes).
• Is Flake 8 compliant (install flake8-docstrings and run flake8 --docstring-convention=all).

Documentation

• [N/A] New features are documented, with examples if plot related.
• [N/A] New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
• [N/A] API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).
• Documentation is sphinx and numpydoc compliant (the docs should build without error).

[oscargus]

Thanks!

Do you have any input on the related issue #23866 ? That is, did you somehow enable the deprecation warnings or did you use a more manual approach?

[StefRe]

Actually I came across this by chance: I was checking in which tutorials and examples the output needs to be captured (for #23796 (comment)). To do so I "grepped" the rst file created by sphinx gallery for .. rst-class:: sphx-glr-script-out. This yielded the deprecation warnings too :). So yes - it's a manual process.

[StefRe]

judging by

matplotlib/doc/conf.py

Lines 50 to 53 in 2171d95

	# Unless we catch the warning explicitly somewhere, a warning should cause the
	# docs build to fail. This is especially useful for getting rid of deprecated
	# usage in the gallery.
	warnings.filterwarnings('error', append=True)

warnings should make the docs build fail, but they don't do so for some reason. Maybe this is due to the append=True if sphinx gallery also controls warnings with the default append value of False? (I didn't check this, just a guess)

[oscargus]

OK!

I have added a step that will at least list examples and tutorials with deprecation warnings in #23868 so that will help a bit.

Thanks for sorting this out!