Handle check_for_updates as unimplemented action

src/apprt/glfw.zig

@@ -249,6 +249,7 @@ pub const App = struct {
             .prompt_title,
             .reset_window_size,
             .ring_bell,
+            .check_for_updates,
             => {
                 log.info("unimplemented action={}", .{action});
                 return false;

src/apprt/gtk/App.zig

@@ -504,6 +504,7 @@ pub fn performAction(
         .renderer_health,
         .color_change,
         .reset_window_size,
+        .check_for_updates,
         => {
             log.warn("unimplemented action={}", .{action});
             return false;