update sdk 31

android/app/build.gradle

@@ -26,7 +26,7 @@ apply plugin: 'com.android.application'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 30
+    compileSdkVersion 31
 
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'
@@ -40,7 +40,7 @@ android {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "tech.soit.flutter_tetris"
         minSdkVersion 21
-        targetSdkVersion 30
+        targetSdkVersion 31
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

android/app/src/main/AndroidManifest.xml

@@ -6,7 +6,7 @@
          additional functionality it is fine to subclass or reimplement
          FlutterApplication and put your custom class here. -->
     <application
-        android:name="io.flutter.app.FlutterApplication"
+        
         android:label="flutter_tetris"
         android:icon="@mipmap/ic_launcher">
         <activity