Use `lowercased()` to fix Xcode autocomplete issue

Sources/TokamakDOM/DOMNode.swift

@@ -40,7 +40,7 @@ extension AnyHTML {
     }
 
     if !containsChecked && dom.ref.type == "checkbox" &&
-      dom.ref.tagName.string!.lowercased == "input"
+      dom.ref.tagName.string!.lowercased() == "input"
     {
       dom.ref.checked = .boolean(false)
     }

Sources/TokamakDemo/ToggleDemo.swift

@@ -20,6 +20,7 @@ public struct ToggleDemo: View {
   public var body: some View {
     VStack {
       Toggle("Check me!", isOn: $checked)
+      Toggle("Toggle binding that should mirror the toggle above", isOn: $checked)
       Toggle(isOn: Binding(get: { true }, set: { _ in })) {
         Group { Text("I’m always checked!").italic() }.foregroundColor(.red)
       }