flake.lib.attrsToList: use implementation from nixpkgs

flake/lib/default.nix

@@ -1,6 +1,6 @@
 lib: rec
 {
-  attrsToList = attrs: builtins.map (name: { inherit name; value = attrs.${name}; }) (builtins.attrNames attrs);
+  inherit (lib) attrsToList;
   mkConditional = condition: trueResult: falseResult: let inherit (lib) mkMerge mkIf; in
     mkMerge [ ( mkIf condition trueResult ) ( mkIf (!condition) falseResult ) ];