minor: use name SVG over extension svg to identify errors

since the extension could be svg or svgz

src/svg.rs

@@ -53,7 +53,7 @@ fn to_image_error(
     e: impl Into<Box<dyn std::error::Error + std::marker::Send + Sync + 'static>>,
 ) -> ImageError {
     ImageError::Decoding(DecodingError::new(
-        image::error::ImageFormatHint::PathExtension("svg".into()),
+        image::error::ImageFormatHint::Name("SVG".into()),
         e,
     ))
 }