ENH: determine compatible matplotlib backend semi-dynamically. Incidentally add support for .svgz image format.

[neutrinoceros]

PR Summary

Drop a hard-coded list of supported file formats and discover them at runtime via Matplotlib instead.
Incidentally, this adds support for saving to .svgz, which is compatible with FigureCanvasSVG but was left out
on our side, likely because it wasn't a thing at the time this code was written. The list of supported file format will then naturally expand if more formats are added upstream, and reciprocally, this avoids creating a situation where we list a format as supported even though it requires a more recent version of Matplotlib than is installed.

This refactor passes yt/visualization/tests/test_commons.py

for reproduction:

import yt
ds = yt.load_sample('IsolatedGalaxy')
yt.PhasePlot(ds, ('gas', 'density')).save("/tmp/", suffix="svgz")

fails on the main branch, but succeeds here

[Xarthisius]

@yt-fido test this please

[neutrinoceros]

I don't remember why you triggered a new job on Jenkins, but I imagine you'd like to revisit this, @Xarthisius ?

[matthewturk]

LGTM; pending question about idioms, good to merge.

[matthewturk]

terribly wrong :)

[matthewturk]

Is this the idiomatic way?

[neutrinoceros]

Yes. It is so idiomatic that it's the only way pyupgrade knows how to clean https://github.com/asottile/pyupgrade#python2-and-old-python3x-blocks
in fact, see : asottile/pyupgrade#530
(notice me sempai !)

[matthewturk]

sounds good

[matthewturk]

I'm good with this post resolution

[neutrinoceros]

Alright I'll resolve the conflict now and come back later to rettriger Jenkins !

[neutrinoceros]

@matthewturk I assume you'd want to use the auto-merge button here :)

[neutrinoceros]

@yt-fido test this please

[matthewturk]

@meeseeksdev backport to yt-4.0.x

[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 yt-4.0.x
$ git pull

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

$ git cherry-pick -m1 c414e45fdcd7ff15afbbe6430ca830e31c704d99

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

$ git commit -am 'Backport PR #3410: ENH: determine compatible matplotlib backend semi-dynamically. Incidentally add support for .svgz image format.'

4. Push to a named branch :

git push YOURFORK yt-4.0.x:auto-backport-of-pr-3410-on-yt-4.0.x

5. Create a PR against branch yt-4.0.x, I would have named this PR:

"Backport PR #3410 on branch yt-4.0.x (ENH: determine compatible matplotlib backend semi-dynamically. Incidentally add support for .svgz image format.)"

And apply the correct labels and milestones.

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

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

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

[neutrinoceros]

@meeseeksdev backport to yt-4.0.x

[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 yt-4.0.x
$ git pull

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

$ git cherry-pick -m1 c414e45fdcd7ff15afbbe6430ca830e31c704d99

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

$ git commit -am 'Backport PR #3410: ENH: determine compatible matplotlib backend semi-dynamically. Incidentally add support for .svgz image format.'

4. Push to a named branch :

git push YOURFORK yt-4.0.x:auto-backport-of-pr-3410-on-yt-4.0.x

5. Create a PR against branch yt-4.0.x, I would have named this PR:

"Backport PR #3410 on branch yt-4.0.x (ENH: determine compatible matplotlib backend semi-dynamically. Incidentally add support for .svgz image format.)"

And apply the correct labels and milestones.

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

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

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

[neutrinoceros]

Backporting this manually with a risk of introducing a new bug in handling the conflict doesn't seem worth it, I'll remove the "Needs Manual Backport label"