Fix broken images on egui.rs (move from git lfs to normal git) (#5480)

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

![image](https://github.com/user-attachments/assets/305e1041-e3e3-472d-9a52-1b90e8da053d)

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

.github/workflows/png_only_on_lfs.yml

@@ -13,11 +13,18 @@ jobs:
     - name: Check that png files are on git LFS
       run: |
         binary_extensions="png"
-        exclude="crates/eframe/data"
+        exclude_paths=(
+          "crates/eframe/data"
+          "crates/egui_demo_lib/data/"
+          "crates/egui/assets/"
+        )
 
         # Find binary files that are not tracked by Git LFS
         for ext in $binary_extensions; do
-          if comm -23 <(git ls-files | grep -v "^$exclude" | sort) <(git lfs ls-files -n | sort) | grep "\.${ext}$"; then
+          # Create grep pattern to exclude multiple paths
+          exclude_pattern=$(printf "|^%s" "${exclude_paths[@]}" | sed 's/^|//')
+
+          if comm -23 <(git ls-files | grep -Ev "$exclude_pattern" | sort) <(git lfs ls-files -n | sort) | grep "\.${ext}$"; then
             echo "Error: Found binary file with extension .$ext not tracked by git LFS. See CONTRIBUTING.md"
             exit 1
           fi