Fixing AOSP tests after AndroidX migration

Test: adb shell am instrument -w -r -e debug false com.android.launcher3.tests/androidx.test.runner.AndroidJUnitRunner
Change-Id: I72bf7095087b012a6eceac71ee02f2d7a5c8c51b
diff --git a/build.gradle b/build.gradle
index dcb5b81..7ac4127 100644
--- a/build.gradle
+++ b/build.gradle
@@ -24,7 +24,7 @@
         versionCode 1
         versionName "1.0"
 
-        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true
     }
     buildTypes {