Pass --disable-embed-rasters to scour

By default, scour embeds raster images (e.g. referenced PNG images) into the SVG image to make the SVG stand-alone.  Unsurprisingly, this tend to make images larger than they were before regardless of how well the SVG cleaner actually work.

tools/stats/src/main.rs

@@ -348,6 +348,7 @@ fn clean_with_scour(exe_path: &str, in_path: &str, out_path: &str) -> bool {
  .arg("--remove-titles")
  .arg("--remove-descriptions")
  .arg("--remove-metadata")
+ .arg("--disable-embed-rasters")
  .output();
 
  match res {