System apps must target API 28 or higher

Bug: 120997004
Change-Id: I998a443a4327c47cbab8e4bc4843be1693f05d8d
diff --git a/go/AndroidManifest.xml b/go/AndroidManifest.xml
index 0080898..25518af 100644
--- a/go/AndroidManifest.xml
+++ b/go/AndroidManifest.xml
@@ -22,7 +22,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     package="com.android.launcher3" >
 
-    <uses-sdk android:targetSdkVersion="23" android:minSdkVersion="21"/>
+    <uses-sdk android:targetSdkVersion="28" android:minSdkVersion="21"/>
 
     <application
         android:backupAgent="com.android.launcher3.LauncherBackupAgent"