Remove reference to egui::Color32. (#5011)

As most of the code refers to types in epaint, it makes sense to use the
Color32 alias from epaint as well.

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crates/egui-wgpu/src/renderer.rs

@@ -542,7 +542,7 @@ impl Renderer {
                     "Mismatch between texture size and texel count"
                 );
                 crate::profile_scope!("font -> sRGBA");
-                Cow::Owned(image.srgba_pixels(None).collect::<Vec<egui::Color32>>())
+                Cow::Owned(image.srgba_pixels(None).collect::<Vec<epaint::Color32>>())
             }
         };
         let data_bytes: &[u8] = bytemuck::cast_slice(data_color32.as_slice());