perf(bukkit): 优化代码

hamster-core-bukkit/src/main/java/cn/hamster3/mc/plugin/core/bukkit/command/ParentCommand.java

@@ -161,7 +161,7 @@ public abstract class ParentCommand extends ChildCommand {
         return childCommands.stream()
                 .filter(o -> o.hasPermission(sender))
                 .map(ChildCommand::getName)
-                .filter(o -> o.toLowerCase().startsWith(args[0]))
+                .filter(o -> o.toLowerCase().startsWith(args[0].toLowerCase()))
                 .collect(Collectors.toList());
     }
 }