add a delay when closing child windows.

tests/Avalonia.IntegrationTests.Appium/ElementExtensions.cs

@@ -140,6 +140,7 @@ namespace Avalonia.IntegrationTests.Appium
                         .First(x => x.Text == newWindowTitle);
                     var (close, _, _) = ((AppiumWebElement)newWindow).GetChromeButtons();
                     close!.Click();
+                    Thread.Sleep(1000);
                 });
             }
         }