Update example app to target version 33

Also setting android:exported to true in the manifest for testing the example app

Author: emawby

example/android/app/build.gradle

@@ -29,7 +29,7 @@ apply plugin: 'com.android.application'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 28
+    compileSdkVersion 33
 
     lintOptions {
         disable 'InvalidPackage'
@@ -39,7 +39,7 @@ android {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "com.onesignal.onesignalexample"
         minSdkVersion 16
-        targetSdkVersion 28
+        targetSdkVersion 33
         versionCode 1
         versionName "1.0"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

example/android/app/src/main/AndroidManifest.xml

@@ -23,6 +23,7 @@
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name=".MainActivity"
+            android:exported="true"
             android:launchMode="singleTop"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density"