update & alias

just `gomod2nix` should work now

shell.nix

@@ -13,14 +13,13 @@
   ),
   mkGoEnv ? pkgs.mkGoEnv,
   gomod2nix ? pkgs.gomod2nix,
-}: let
-  update_gomod2nix = pkgs.writeShellScriptBin "update_gomod2nix" ''
-    ${gomod2nix}/bin/gomod2nix --dir ${source} --outdir ./
+}:
+pkgs.mkShell {
+  buildInputs = [
+    gomod2nix
+  ];
+  shellHook = ''
+    alias gomod2nix='${gomod2nix}/bin/gomod2nix --dir ${source} --outdir ./'
   '';
-in
-  pkgs.mkShell {
-    packages = [
-      gomod2nix
-      update_gomod2nix
-    ];
-  }
+  packages = [];
+}