Linux: Failing to load 32bpp BMP previously exported from Aseprite.

[sammynilla]

Pixelorama version:
v0.10.3

Issue description:
I'm currently trying to load a bitmap file that was previously exported from Aseprite v1.2.40-dev that was built from source as I'm looking into alternative art programs, but I'm being greeted with error code 16. At first I thought that maybe I had accidentally exported my bitmap as a 16bpp image, which isn't supported via Godot's built-in asset pipeline, but I analyzed the image a few moments ago and it actually is 32bpp.

The exported bitmap will not load properly if you choose to create a new sprite with a background that is transparent, regardless of if you fill in the background afterwards or not.

Extra Notes:
There seems to be different behaviors among different art programs.

• The bitmaps will load properly via Pixelorama if you do the same thing, but choose to start with the sprite filled with white or black.
• Both versions load into Aseprite properly, but the image will load in filled with a black color in place of a transparent background.
• Both versions also load into GIMP properly, but the image will load in with an actual transparent background.

Steps to reproduce:

• The image I'm failing to load is available to see here if Aseprite is unavailable to whomever may be trying to reproduce my bug.
• However, if you have Aseprite v1.2.40-dev available, just open it up, create a new sprite with RGBA and transparent background, and fill the background with your color of choosing before exporting it as a bitmap.
• Try to load it in Pixelorama.