chore: add gopls.

shell.nix

@@ -4,22 +4,21 @@
       inherit (builtins) fetchTree fromJSON readFile;
       inherit ((fromJSON (readFile ./flake.lock)).nodes) nixpkgs gomod2nix;
     in
-    import (fetchTree nixpkgs.locked) {
-      overlays = [
-        (import "${fetchTree gomod2nix.locked}/overlay.nix")
-      ];
-    }
+      import (fetchTree nixpkgs.locked) {
+        overlays = [
+          (import "${fetchTree gomod2nix.locked}/overlay.nix")
+        ];
+      }
   ),
   mkGoEnv ? pkgs.mkGoEnv,
   gomod2nix ? pkgs.gomod2nix,
-}:
-
-let
-  goEnv = mkGoEnv { pwd = ./.; };
+}: let
+  goEnv = mkGoEnv {pwd = ./.;};
 in
-pkgs.mkShell {
-  packages = [
-    goEnv
-    gomod2nix
-  ];
-}
+  pkgs.mkShell {
+    packages = [
+      goEnv
+      gomod2nix
+      pkgs.gopls
+    ];
+  }