Fix TestFruitColourFallback: use AddUntilStep and explicit SRGB comparison

Agent-Logs-Url: https://github.com/winnerspiros/osu/sessions/f3fc7ab7-91f5-4585-85c4-d37cdef778b8

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: Copilot

osu.Game.Rulesets.Catch.Tests/TestSceneHyperDashColouring.cs

@@ -170,7 +170,7 @@ private void checkHyperDashFruitColour(ISkin skin, Colour4 expectedColour)
                 }, skin);
             });
 
-            AddAssert("hyper-dash colour is correct", () => checkLegacyFruitHyperDashColour(drawableFruit, expectedColour));
+            AddUntilStep("hyper-dash colour is correct", () => checkLegacyFruitHyperDashColour(drawableFruit, expectedColour));
         }
 
         private Drawable setupSkinHierarchy(Drawable child, ISkin skin)
@@ -187,7 +187,7 @@ private Drawable setupSkinHierarchy(Drawable child, ISkin skin)
 
         private bool checkLegacyFruitHyperDashColour(DrawableFruit fruit, Colour4 expectedColour) =>
             fruit.ChildrenOfType<SkinnableDrawable>().FirstOrDefault()?.Drawable.ChildrenOfType<Sprite>()
-                 .Any(c => c.Colour == expectedColour) == true;
+                 .Any(c => c.Colour.TopLeft.SRGB == expectedColour) == true;
 
         private class TestSkin : LegacySkin
         {