cur file saved as a png has black pixels where it needs to be transparent

its a really easy-to-reproduce issue, just run this code with the file i attached in Pillow 12.1.0 : ```python from PIL import Image im = Image.open("aero_unavail.cur") im.save("aero_unavail.png") ``` (the file is provided as a txt file since github doesn't allow cur files to be uploaded, just change the extension.) [aero_unavail.txt](https://github.com/user-attachments/files/28198662/aero_unavail.txt)