replace nixos-rebuild aliases -> nh os

nixpkgs.nix

@@ -11,7 +11,6 @@
         (import ./overlays args)
       ];
       config = {
-        # allowUnfree = false;
         allowBroken = false;
         allowUnfreePredicate = pkg:
           builtins.elem (lib.getName pkg) [
@@ -40,5 +39,16 @@
         allowBroken = false;
       };
     };
+
+    # nixpkgs-master
+    mpkgs = {
+      inherit system;
+      source = inputs.nixpkgs-master;
+      overlays = [];
+      config = {
+        allowUnfree = false;
+        allowBroken = false;
+      };
+    };
   };
 }