Fix caption dialog context menu background (#3787)

Fixes #3770, #3491

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

@@ -98,7 +98,7 @@
     <style name="TuskyDialog" parent="@style/ThemeOverlay.MaterialComponents.Dialog.Alert">
         <item name="android:letterSpacing">0</item>
         <item name="dialogCornerRadius">8dp</item>
-        <item name="android:background">@color/colorBackground</item>
+        <item name="android:colorBackground">@color/colorBackground</item>
     </style>
 
     <style name="TuskyDialogFragmentStyle" parent="@style/ThemeOverlay.MaterialComponents.Dialog">