Update build.gradle

Author: slightfoot

example/android/app/build.gradle

@@ -15,8 +15,7 @@ apply plugin: 'com.android.application'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 28
-    buildToolsVersion '28.0.3'
+    compileSdkVersion 27
 
     lintOptions {
         disable 'InvalidPackage'
@@ -44,7 +43,7 @@ flutter {
 }
 
 dependencies {
-    androidTestImplementation 'com.android.support:support-annotations:28.0.0'
+    androidTestImplementation 'com.android.support:support-annotations:27.0.0'
     androidTestImplementation 'com.android.support.test:runner:1.0.2'
     androidTestImplementation 'com.android.support.test:rules:1.0.2'
 }