Remove letter spacing from buttons (fixes #2696)

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

@@ -189,6 +189,10 @@
     <!--==============-->
     <!--Widgets.Button-->
     <!--==============-->
+    <style name="TextAppearance.Widget.Button" parent="TextAppearance.MaterialComponents.Button">
+        <item name="android:letterSpacing">0</item>
+    </style>
+
     <style name="Theme.Widget.Button" parent="Widget.MaterialComponents.Button.TextButton">
         <item name="android:textColor">?attr/colorOnSurface</item>
     </style>

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

@@ -48,6 +48,7 @@
         <item name="preferenceTheme">@style/PreferenceThemeOverlay</item>
         <item name="dialogTheme">@style/Theme.AlertDialog.Light</item>
         <item name="alertDialogTheme">@style/Theme.AlertDialog.Dark</item>
+        <item name="textAppearanceButton">@style/TextAppearance.Widget.Button</item>
 
         <!-- Custom Attributes-->
         <item name="selectable_library_drawable">@drawable/library_item_selector_light</item>
@@ -99,6 +100,8 @@
         <item name="preferenceTheme">@style/PreferenceThemeOverlay</item>
         <item name="dialogTheme">@style/Theme.AlertDialog.Dark</item>
         <item name="alertDialogTheme">@style/Theme.AlertDialog.Dark</item>
+        <item name="textAppearanceButton">@style/TextAppearance.Widget.Button</item>
+
         <item name="md_background_color">?attr/colorSurface</item>
 
         <!-- Custom Attributes-->