Fix broken images on egui.rs (move from git lfs to normal git)

[emilk]

The images in the widget gallery on egui.rs are broken:

Not sure why yet, and I fail to reproduce locally.
It's because they are on git lfs.

[github-actions]

Preview available at https://egui-pr-preview.github.io/pr/5480-emilkfix-images-maybe
Note that it might take a couple seconds for the update to show up after the preview_build workflow has completed.

[lucasmerlin]

Could it be that things aren't checked out with lfs for the web build? The error suggests that image couldn't detect the format which would make sense if the image has the lfs text contents

[InfoInnovator]

I really dont want to intervene here, but @lucasmerlin might be right. I cannot even open the image with my standard image viewer. If i copy the image from the eframe/data to egui_demo_lib/data it works.

[lucasmerlin]

@InfoInnovator if you have this problem locally, make sure you have properly setup git lfs.

[InfoInnovator]

@InfoInnovator if you have this problem locally, make sure you have properly setup git lfs.

My bad. I didnt expect somebody to use lfs for a small PNG and didnt know of the guide. After pulling the lfs files, the web demo works as intended.

[emilk]

Ah, then we should mark the .png:s used for the demo as non-lfs, and also see if we can improve the error message (does lfs links start with some magic bytes?)

[lucasmerlin]

(does lfs links start with some magic bytes?)

I think so:

version https://git-lfs.github.com/spec/v1
oid sha256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393
size 12345

[emilk]

Improvement!

[emilk]

Fixed! Just need to update CI not to complain