[DO NOT MERGE] Bump Contacts to 1.4.21 and targetSdkVersion as 24.

BUG 28555200

Change-Id: Ia9ff1d5391a2015dce418eebc9637318ddc4f771
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 3af383d..e92b69c 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -16,10 +16,10 @@
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.android.contacts"
-    android:versionCode="10420"
-    android:versionName="1.4.20">
+    android:versionCode="10421"
+    android:versionName="1.4.21">
 
-    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="23" />
+    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="24" />
     <original-package android:name="com.android.contacts" />
 
     <uses-permission android:name="android.permission.CALL_PHONE" />