feat(popover-content): add aria-modal attr

Co-authored-by: Giorgio Boa <[email protected]>

Author: igalklebanov

packages/kit-headless/src/components/popover/popover-content.tsx

@@ -19,7 +19,7 @@ export const PopoverContent = component$(() => {
   });
 
   return (
-    <div ref={ref} role="dialog" class="popover-content">
+    <div ref={ref} role="dialog" aria-modal="true" class="popover-content">
       <Slot />
     </div>
   );