message: add feature gate
diff: @@ -872,6 +872,7 @@ mod tests {
  }
  #[test]
  + #[cfg(feature = "png")]
  fn resize_transparent_image() {
  use super::FilterType::{CatmullRom, Gaussian, Lanczos3, Nearest, Triangle};
  use crate::imageops::crop_imm;
  