avisynthplus: drop `libdevil` dependency

Optional dependency, used only for the `ImageSeq` plugin.

pkgs/by-name/av/avisynthplus/package.nix

···
   cmake,
   pkg-config,
   gitUpdater,
-  libdevil,
   soundtouch,
 }:
 
···
   '';
 
   buildInputs = [
-    libdevil
     soundtouch
   ];