System apps must target API 28 or higher

Bug: 120997004
Change-Id: I998a443a4327c47cbab8e4bc4843be1693f05d8d
diff --git a/tests/AndroidManifest.xml b/tests/AndroidManifest.xml
index 0be5f11..ebab122 100644
--- a/tests/AndroidManifest.xml
+++ b/tests/AndroidManifest.xml
@@ -18,7 +18,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     package="com.android.launcher3.tests">
 
-    <uses-sdk android:targetSdkVersion="25" android:minSdkVersion="21"
+    <uses-sdk android:targetSdkVersion="28" android:minSdkVersion="21"
               tools:overrideLibrary="android.support.test.uiautomator.v18"/>
 
     <application android:debuggable="true">