feat(flake): add disko to flake.nix for nixos-anywhere

flake.nix

@@ -35,6 +35,11 @@
       url = "github:Mic92/sops-nix";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+
+    disko = {
+      url = "github:nix-community/disko";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =