fix: resolve 'system' deprecation warning in default.nix (#8)

Author: jWXZSCsqrpZRSVwauBjn

distro/nix/default.nix

@@ -12,7 +12,7 @@ let
 in {
   options.programs.dsearch = {
     enable = mkEnableOption "danksearch";
-    package = mkPackageOption self.packages.${pkgs.system} "dsearch" { };
+    package = mkPackageOption self.packages.${pkgs.stdenv.hostPlatform.system} "dsearch" { };
 
     config = mkOption {
       type = types.nullOr tomlFormat.type;