Update art submodule commit version

[Lasercar]

Does this PR close any issues? If so, link them below.

Briefly describe the issue(s) fixed.

I've had to avoid accidentally including the new commit version of the art assets in my commits, so here's a PR to just update it on it's own.

I'm a little surprised that no one noticed or has fixed this already.

Ah yes, github bot, yes, this is definitely a 'small' commit (it totally doesn't add 100 new files). /s

Include any relevant screenshots or videos.

[Hundrec]

Can you elaborate on what this PR solves? I didn't quite understand your explanation, and we generally don't merge PRs modifying submodules.

[Lasercar]

This PR fixes this:

If I click 'stage changed' it includes the updated art submodule and I have to unstage it or else accidentally have it included in one of my commits.

Hence, this PR to just update it.
You could probably ask @EliteMasterEric to update it though (but then again, I did notice this first...).

[Hundrec]

Okay, I'll ask Eric about this and get back to you

[Lasercar]

I did not expect this to be my first merged contribution

[Lasercar]

Oh, also, you might want to consider doing this for the develop branch as well. This is done now.