refactor: specify missing type

Author: mlopezFC

src/test/java/com/flowingcode/vaadin/addons/chatassistant/ChatAssistantMarkdownDemo.java

@@ -39,7 +39,7 @@
 public class ChatAssistantMarkdownDemo extends VerticalLayout {
 
   public ChatAssistantMarkdownDemo() {
-    ChatAssistant chatAssistant = new ChatAssistant(true);
+    ChatAssistant<Message> chatAssistant = new ChatAssistant<>(true);
     TextArea message = new TextArea();
     message.setLabel("Enter a message from the assistant (try using Markdown)");
     message.setSizeFull();