Log Message:
ImageMagick: update to 7.1.0.4.

2021-07-18  7.1.0-4  <quetzlzacatenango@image...>
  * Release ImageMagick version 7.1.0-4 GIT revision 18926:8eb9c6c48:20210718

2021-07-17  7.1.0-4  <quetzlzacatenango@image...>
  * trim no longer returns an empty image on 1-pixel width input (reference
    https://github.com/ImageMagick/ImageMagick/issues/3896).
  * remove virtual canvas offset from difference image.

2021-07-17  7.1.0-3  <quetzlzacatenango@image...>
  * Release ImageMagick version 7.1.0-3 GIT revision 18901:692e6e059:20210717

2021-07-03  7.1.0-3  Dirk Lemstra <dirk@lem.....org>
  * Added option to set the pixel format option of ffmpeg when reading a
    video file with -define video:pixel-format=<value>.

2021-06-26  7.1.0-3  <quetzlzacatenango@image...>
  * system() is not supported under IOS.
  * accelerate subimage-search with FFT's (contributed by Fred).