Fix flake resolution issues due to unpinned go version

flake.nix

@@ -2,6 +2,7 @@
   description = "A utility for generating Mermaid diagrams from Terraform configurations";
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    nixpkgs-go.url = "github:nixos/nixpkgs/ef9ca28baceba7da849e0fdb18bab8d3173fd208";
     flake-utils.url = "github:numtide/flake-utils";
 
     gomod2nix = {
@@ -15,13 +16,19 @@
   outputs = {
     self,
     nixpkgs,
+    nixpkgs-go,
     flake-utils,
     gomod2nix,
   }:
     flake-utils.lib.eachDefaultSystem (system: let
       pkgs = import nixpkgs {
         inherit system;
-        overlays = [gomod2nix.overlays.default];
+        overlays = [
+          gomod2nix.overlays.default
+          (final: prev: {
+            go = nixpkgs-go.packages.${system}.go;
+          })
+        ];
       };
       callPackage = pkgs.callPackage;
     in {
@@ -35,7 +42,11 @@
     // {
       overlays.default = final: prev: {
         terramaid = import ./default.nix {
-          pkgs = final.extend gomod2nix.overlays.default;
+          pkgs =
+            (final.extend gomod2nix.overlays.default).extend
+            (final: prev: {
+              go = nixpkgs-go.packages.${final.stdenv.hostPlatform.system}.go;
+            });
         };
       };
     };