chore: Amplify Flutter v1 messaging (#8386)

Author: tyllark

src/fragments/lib-v1/flutter-maintenance.mdx

@@ -1,6 +1,6 @@
 <Callout warning>
 
-Amplify Flutter v1 is now in **Maintenance Mode** until April 30th, 2025. This means that we will continue to include updates to ensure compatibility with backend services and security. No new features will be introduced in v1.
+Amplify Flutter v1 is **deprecated** as of April 30th, 2025. No new features or bug fixes will be added. Dependencies may become outdated and potentially introduce compatibility issues.
 
 Please use the latest version (v2) of [Amplify Flutter](/gen1/[platform]/tools/libraries/) to get started.