Remove unused class and resource

uhabits-android/src/main/res/drawable/shadow.xml

@@ -1,28 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-  ~ Copyright (C) 2016-2021 Álinson Santos Xavier <git@axavier.org>
-  ~
-  ~ This file is part of Loop Habit Tracker.
-  ~
-  ~ Loop Habit Tracker is free software: you can redistribute it and/or modify
-  ~ it under the terms of the GNU General Public License as published by the
-  ~ Free Software Foundation, either version 3 of the License, or (at your
-  ~ option) any later version.
-  ~
-  ~ Loop Habit Tracker is distributed in the hope that it will be useful, but
-  ~ WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
-  ~ or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
-  ~ more details.
-  ~
-  ~ You should have received a copy of the GNU General Public License along
-  ~ with this program. If not, see <http://www.gnu.org/licenses/>.
-  -->
-
-<shape xmlns:android="http://schemas.android.com/apk/res/android"
-       android:shape="rectangle">
-
-    <gradient android:startColor="@android:color/transparent"
-              android:endColor="@color/black"
-              android:angle="90"/>
-
-</shape>

uhabits-android/src/main/res/values/styles.xml

@@ -203,13 +203,6 @@
         <item name="android:layout">@layout/preference_category_custom</item>
     </style>
 
-    <style name="ToolbarShadow">
-        <item name="android:layout_width">match_parent</item>
-        <item name="android:layout_height">2dp</item>
-        <item name="android:background">@drawable/shadow</item>
-        <item name="android:alpha">0.2</item>
-    </style>
-
     <style name="DialogWithTitle" parent="@style/Theme.AppCompat.Light.Dialog">
         <item name="windowNoTitle">false</item>
     </style>