Try to fix CI

sparse_strips/vello_common/src/pixmap.rs

diff --git a/sparse_strips/vello_common/src/pixmap.rs b/sparse_strips/vello_common/src/pixmap.rs
index 59feb9d..4567ecd 100644
--- a/sparse_strips/vello_common/src/pixmap.rs
+++ b/sparse_strips/vello_common/src/pixmap.rs
@@ -191,7 +191,7 @@
 
         Ok(pixmap)
     }
-    
+
     /// Return the current content of the pixmap as a PNG.
     #[cfg(feature = "png")]
     pub fn take_png(self) -> Result<Vec<u8>, png::EncodingError> {

sparse_strips/vello_sparse_tests/tests/util.rs

diff --git a/sparse_strips/vello_sparse_tests/tests/util.rs b/sparse_strips/vello_sparse_tests/tests/util.rs
index 0afbc11..2d270fd 100644
--- a/sparse_strips/vello_sparse_tests/tests/util.rs
+++ b/sparse_strips/vello_sparse_tests/tests/util.rs
@@ -4,13 +4,11 @@
 //! Utility functions shared across different tests.
 
 use crate::renderer::Renderer;
-use image::codecs::png::PngEncoder;
-use image::{ExtendedColorType, ImageEncoder, Rgba, RgbaImage, load_from_memory};
+use image::{Rgba, RgbaImage, load_from_memory};
 use skrifa::MetadataProvider;
 use skrifa::raw::FileRef;
 use smallvec::smallvec;
 use std::cmp::max;
-use std::io::Cursor;
 use std::sync::Arc;
 use vello_common::color::DynamicColor;
 use vello_common::color::palette::css::{BLUE, GREEN, RED, WHITE, YELLOW};
@@ -335,7 +333,7 @@
     assert!(!is_reference, "WASM cannot create new reference images");
 
     let pixmap = render_pixmap(ctx, render_mode);
-    let encoded_image = pixmap_to_png(pixmap, ctx.width() as u32, ctx.height() as u32);
+    let encoded_image = pixmap.take_png().unwrap();
     let actual = load_from_memory(&encoded_image).unwrap().into_rgba8();
 
     let ref_image = load_from_memory(ref_data).unwrap().into_rgba8();