/usr/lib/libGraphicsMagick.so is in libgraphicsmagick1-dev 1.3.28-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libGraphicsMagick-Q16.so.3.17.2
/usr/lib/libGraphicsMagick-Q16.so.3.17.2