可以指定 `closable` 属性为 `true` 来允许提示被用户主动关闭，还可以通过指定 `close-label` 属性来将关闭按钮以文字形式展现。 Set the `closable` prop to `true` to allow the alert message to be closed by users. You can also use the `close-label` prop to make the close button shown as specified text.