Make use of CopyOnWriteArray instead

This is automatically safe for iterations (which Collections.synchronizedList is not)
	and it makes more sense for our use case given the rarity of our writes

src/main/java/com/questhelper/panel/QuestOverviewPanel.java

@@ -40,6 +40,7 @@
 import java.awt.event.ItemEvent;
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
@@ -95,7 +96,7 @@ public class QuestOverviewPanel extends JPanel
 
 	private final JButton collapseBtn = new JButton();
 
-	private final List<QuestStepPanel> questStepPanelList = Collections.synchronizedList(new ArrayList<>());
+	private final List<QuestStepPanel> questStepPanelList = new CopyOnWriteArrayList<>();
 
 	public QuestOverviewPanel(QuestHelperPlugin questHelperPlugin, QuestManager questManager)
 	{