apprt/glfw,gtk: noop undo/redo actions

src/apprt/glfw.zig

@@ -250,6 +250,8 @@ pub const App = struct {
             .reset_window_size,
             .ring_bell,
             .check_for_updates,
+            .undo,
+            .redo,
             .show_gtk_inspector,
             => {
                 log.info("unimplemented action={}", .{action});

src/apprt/gtk/App.zig

@@ -515,6 +515,8 @@ pub fn performAction(
         .color_change,
         .reset_window_size,
         .check_for_updates,
+        .undo,
+        .redo,
         => {
             log.warn("unimplemented action={}", .{action});
             return false;