chore: update supported versions for flat page plugin

Author: panakour

content/plugins/panakour-flat-page.md

@@ -9,6 +9,6 @@ docs_url: https://raw.githubusercontent.com/panakour/filament-flat-page/main/REA
 github_repository: panakour/filament-flat-page
 has_dark_theme: true
 has_translations: true
-versions: [3]
+versions: [3, 4]
 publish_date: 2024-10-20
 ---