nexusmods-app: remove copyDesktopItems hook

We don't need this hook, because the desktop entries come from `src` and
don't need to be copied from `desktopItems` inputs.

See https://nixos.org/manual/nixpkgs/unstable/#trivial-builder-makeDesktopItem
for valid usage of `copyDesktopItems`.

pkgs/by-name/ne/nexusmods-app/package.nix

@@ -2,7 +2,6 @@
   _7zz,
   avalonia,
   buildDotnetModule,
-  copyDesktopItems,
   desktop-file-utils,
   dotnetCorePackages,
   fetchgit,
@@ -51,7 +50,6 @@ buildDotnetModule (finalAttrs: {
   nativeCheckInputs = [ _7zz ];
 
   nativeBuildInputs = [
-    copyDesktopItems
     imagemagick # For resizing SVG icon in postInstall
   ];