make additional test for C# like Java-Approvals

csharp.xUnit/GildedRoseTests/ApprovalTest.cs

@@ -13,6 +13,16 @@ namespace GildedRoseTests;
 
 public class ApprovalTest
 {
+    [Fact]
+    public Task Foo()
+    {
+        Item[] items = { new Item { Name = "foo", SellIn = 0, Quality = 0 } };
+        GildedRose app = new GildedRose(items);
+        app.UpdateQuality();
+        
+        return Verifier.Verify(items);
+    }
+    
     [Fact]
     public Task ThirtyDays()
     {