fix: revert AGP 9 to 8.13.2 - Flutter plugins not yet compatible with AGP 9

android/app/build.gradle.kts

@@ -3,6 +3,7 @@ import java.io.FileInputStream
 
 plugins {
     id("com.android.application")
+    id("kotlin-android")
     // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
     id("dev.flutter.flutter-gradle-plugin")
 }