do not allow to backup data by Google

Why:

 * During backup process Termux is being killed in most cases.
 * Backup data is limited to 25 MB.
 * Backup may not be performed/updated in certain cases.

Author: Leonid Plyushch

app/src/main/AndroidManifest.xml

@@ -18,8 +18,7 @@
 
     <application
         android:extractNativeLibs="true"
-        android:allowBackup="true"
-        android:fullBackupContent="@xml/backupscheme"
+        android:allowBackup="false"
         android:icon="@drawable/ic_launcher"
         android:banner="@drawable/banner"
         android:label="@string/application_name"