target Android SdkVersion 28

Source/Android/app/build.gradle

@@ -1,7 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
-    compileSdkVersion 27
+    compileSdkVersion 28
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_8
@@ -22,7 +22,7 @@ android {
         // TODO If this is ever modified, change application_id in strings.xml
         applicationId "org.dolphinemu.dolphinemu"
         minSdkVersion 21
-        targetSdkVersion 27
+        targetSdkVersion 28
 
         versionCode(getBuildVersionCode())