LibWeb: Correct forward for UIEvents::UIEvent

Author: https://github.com/jamierocks
Commit: https://github.com/LadybirdBrowser/ladybird/commit/60d9c3929cc
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/701
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/AtkinsSJ
Reviewed-by: https://github.com/tcl3

Userland/Libraries/LibWeb/Forward.h

@@ -729,7 +729,7 @@ namespace Web::UIEvents {
 class KeyboardEvent;
 class MouseEvent;
 class PointerEvent;
-class UIEvents;
+class UIEvent;
 }
 
 namespace Web::DOMURL {