digikam: enable appstyles

Without this digikam forces the fusion style.

pkgs/applications/graphics/digikam/default.nix

@@ -116,6 +116,7 @@ mkDerivation rec {
     "-DENABLE_INTERNALMYSQL=1"
     "-DENABLE_MEDIAPLAYER=1"
     "-DENABLE_QWEBENGINE=on"
+    "-DENABLE_APPSTYLES=on"
   ];
 
   dontWrapGApps = true;