Fix tests failing after merge.

tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests_Multiple.cs

@@ -1100,7 +1100,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             {
                 Template = Template(),
                 Items = new[] { "Foo", "Bar", "Baz" },
-                ItemTemplate = new FuncDataTemplate<string>(x => new TextBlock { Width = 20, Height = 10 }),
+                ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                 SelectionMode = SelectionMode.Multiple,
             };
 
@@ -1120,7 +1120,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
             {
                 Template = Template(),
                 Items = new[] { "Foo", "Bar", "Baz" },
-                ItemTemplate = new FuncDataTemplate<string>(x => new TextBlock { Width = 20, Height = 10 }),
+                ItemTemplate = new FuncDataTemplate<string>((x, _) => new TextBlock { Width = 20, Height = 10 }),
                 SelectionMode = SelectionMode.Multiple,
             };