[#70] Fix gamma correction shader image format

projects/voxelization/resources/shaders/gammaCorrection.comp

 #version 440
 
-layout(set=0, binding=0, r8) uniform image2D sceneImage;
+layout(set=0, binding=0, rgba8) uniform image2D sceneImage;
 
 layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;