Fix indentation.

nixos/modules/services/x11/display-managers/gdm.nix

···
 
     systemd.services.display-manager.conflicts = [ "[e-mail]" ];
     systemd.services.display-manager.serviceConfig = {
-        # Restart = "always"; - already defined in xserver.nix
-        KillMode = "mixed";
-        IgnoreSIGPIPE = "no";
-        BusName = "org.gnome.DisplayManager";
-        StandardOutput = "syslog";
-        StandardError = "inherit";
+      # Restart = "always"; - already defined in xserver.nix
+      KillMode = "mixed";
+      IgnoreSIGPIPE = "no";
+      BusName = "org.gnome.DisplayManager";
+      StandardOutput = "syslog";
+      StandardError = "inherit";
     };
 
     systemd.services.display-manager.path = [ gnome3.gnome_session ];