fix(deps): update dependency flutter_local_notifications to v21

Author: renovate[bot]

packages/neon_framework/pubspec.yaml

@@ -33,7 +33,7 @@ dependencies:
     sdk: flutter
   flutter_bloc: ^9.0.0
   flutter_blurhash: ^0.9.0
-  flutter_local_notifications: ^19.0.0
+  flutter_local_notifications: 21.0.0
   flutter_localizations:
     sdk: flutter
   flutter_material_design_icons: ^1.1.7296