feat(deertopia): Set trusted-users

hosts/deertopia/configuration.nix

@@ -105,6 +105,21 @@
   # TODO: Move to defaults.
   users.mutableUsers = false;
 
+  nix = {
+    settings = {
+      trusted-users = [
+        "@wheel"
+      ];
+      substituters = [
+        "https://nix-community.cachix.org"
+        "https://cache.nixos.org"
+      ];
+      trusted-public-keys = [
+        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+      ];
+    };
+  };
+
   # This option defines the first version of NixOS you have installed on this
   # particular machine, and is used to maintain compatibility with application
   # data (e.g. databases) created on older NixOS versions.