Change targetSdk to 28

Also bump versions.

Test: built and launched the app on Walleye running P
Bug: 76092272

Change-Id: I8ee06951caf4f7f392e39f0b3f8c8b4da202ce9f
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 1476e89..df17359 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -16,12 +16,12 @@
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
           package="com.android.contacts"
-          android:versionCode="10730"
-          android:versionName="1.7.30">
+          android:versionCode="10731"
+          android:versionName="1.7.31">
 
     <uses-sdk
         android:minSdkVersion="21"
-        android:targetSdkVersion="25"/>
+        android:targetSdkVersion="28"/>
 
     <original-package android:name="com.android.contacts"/>