Do blending in srgb space (for HelloPaint)

crates/egui-wgpu/src/lib.rs

@@ -324,7 +324,7 @@ pub fn preferred_framebuffer_format(
     for &format in formats {
         if matches!(
             format,
-            wgpu::TextureFormat::Rgba8Unorm | wgpu::TextureFormat::Bgra8Unorm
+            wgpu::TextureFormat::Rgba8UnormSrgb | wgpu::TextureFormat::Bgra8UnormSrgb
         ) {
             return Ok(format);
         }