Set usesCleartextTraffic to false already

It will default to false once we're targeting SDK 28 or higher, but
we might as well set it already for best security for our users.
(Not that this app does any network requests at all)

Author: pcolby

app/src/main/AndroidManifest.xml

@@ -14,6 +14,7 @@
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
+        android:usesCleartextTraffic="false"
         tools:targetApi="35">
 
         <activity