fix: agenix on nix-darwin, update flake.nix

modules/base.nix

@@ -29,25 +29,6 @@
     builders-use-substitutes = true;
   };
 
-  # do garbage collection weekly to keep disk usage low
-  nix.gc =
-    {
-      automatic = lib.mkDefault true;
-      options = lib.mkDefault "--delete-older-than 7d";
-    }
-    // (
-      if pkgs.stdenv.isLinux
-      then {
-        dates = lib.mkDefault "weekly";
-      }
-      else {
-        # nix-darwin
-        interval = {
-          Hour = 24;
-        };
-      }
-    );
-
   # Allow unfree packages
   nixpkgs.config.allowUnfree = lib.mkDefault false;
 }