Remove deprecated preferenceTheme style attribute

Author: TacoTheDank

app/src/main/res/values/styles.xml

@@ -16,7 +16,6 @@
         <item name="actionColor">@color/white</item>
         <item name="floatingActionButtonStyle">@style/FloatingActionButtonTheme</item>
         <item name="toolbarSearchColor">@color/white</item>
-        <item name="preferenceTheme">@style/PreferenceThemeOverlay.v14.Material</item>
         <item name="colorControlActivated">?attr/colorPrimary</item>
     </style>
     <style name="Base" parent="Base.V19"/>