flutter_local_notifications-v13.0.0

• [Android] Bumped Android Gradle plugin to 7.3.1. Thanks to the PR from Rexios
• • Updated minimum Flutter version to 3.0.0. Note that technically this was already a requirement by flutter_local_notifications_linux 2.0.0 as ffi 2.0.0 requires Dart 2.17 at a minimum and that shipped with Flutter 3.0.0
• Added explicit ffi dependency that Linux implementation of the plugin was already using
• Updated site used by example app to display dummy/placeholder images
• Updated readme to warn developers that choose not to follow the official Android guidance around notification icons that using the @mipmap/ic_launcher resource requires additional release build configuration. Thanks to the PR from Daniel Arndt
• Updated readme to add note about how Flutter has an issue with apps running with desugaring on Android 12L and above. Thanks to the PR from Mirek Mazel See flutter/flutter#110658. One potential fix added to the readme is for apps to add the WindowManager library as a dependency:

dependencies {
    implementation 'androidx.window:window:1.0.0'
    implementation 'androidx.window:window-java:1.0.0'
    ...
}