previewqt: drop `libdevil` dependency

Optional dependency along with like ten other format‐reading
libraries, including our favourite FreeImage.

Emily 5451732f b4a04a92

-2
-2
pkgs/by-name/pr/previewqt/package.nix
··· 6 fetchFromGitLab, 7 imagemagick, 8 libarchive, 9 - libdevil, 10 libraw, 11 mpv, 12 pkg-config, ··· 38 exiv2 39 imagemagick 40 libarchive 41 - libdevil 42 libraw 43 mpv 44 resvg
··· 6 fetchFromGitLab, 7 imagemagick, 8 libarchive, 9 libraw, 10 mpv, 11 pkg-config, ··· 37 exiv2 38 imagemagick 39 libarchive 40 libraw 41 mpv 42 resvg