message: Add new magic byte
  Add compatibility with .avif files created via libheif
diff: @@ -252,7 +252,7 @@ pub(crate) fn write_buffer_impl<W: std::io::Write + Seek>(
  }
  }
  -static MAGIC_BYTES: [(&[u8], ImageFormat); 21] = [
  +static MAGIC_BYTES: [(&[u8], ImageFormat); 22] = [
  (b"\x89PNG\r\n\x1a\n", ImageFormat::Png),
  (&[0xff, 0xd8, 0xff], ImageFormat::Jpeg),
  (b"GIF89a", ImageFormat::Gif),
  @@ -273,6 +273,7 @@ static MAGIC_BYTES: [(&[u8], ImageFormat); 21] = [
  (b"P7", ImageFormat::Pnm),
  (b"farbfeld", ImageFormat::Farbfeld),
  (b"\0\0\0 ftypavif", ImageFormat::Avif),
  + (b"\0\0\0\x1cftypavif", ImageFormat::Avif),
  (&[0x76, 0x2f, 0x31, 0x01], ImageFormat::OpenExr), // = &exr::meta::magic_number::BYTES
  ];
  