Add missing OverlayColourProvider in test scene

osu.Game.Tests/Visual/UserInterface/TestSceneFirstRunScreenUIScale.cs

@@ -1,13 +1,18 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using osu.Framework.Allocation;
 using osu.Framework.Screens;
+using osu.Game.Overlays;
 using osu.Game.Overlays.FirstRunSetup;
 
 namespace osu.Game.Tests.Visual.UserInterface
 {
     public class TestSceneFirstRunScreenUIScale : OsuManualInputManagerTestScene
     {
+        [Cached]
+        private OverlayColourProvider colourProvider = new OverlayColourProvider(OverlayColourScheme.Purple);
+
         public TestSceneFirstRunScreenUIScale()
         {
             AddStep("load screen", () =>