Add nix-gc-env input

flake.nix

@@ -11,6 +11,8 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
 
+    nix-gc-env.url= "github:Julow/nix-gc-env";
+
     home-manager = {
       url = "github:nix-community/home-manager";
       inputs.nixpkgs.follows = "nixpkgs";