“新版本‘18.04.5 LTS’可用。”升級到 18.04.5 後仍保留該訊息

Question

我只是透過命令將 ubuntu 16.xx（16.04 或 16.10）升級到 18.04 sudo do-release-upgrade。歡迎訊息顯示我已升級到18.04.5，但「新版本可用」訊息仍然保留。

Welcome to Ubuntu 18.04.5 LTS (GNU/Linux 4.4.0-209-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage
New release '18.04.5 LTS' available.
Run 'do-release-upgrade' to upgrade to it.
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.5 LTS
Release:        18.04
Codename:       bionic

難道我的升級失敗了？如何查看我的系統是否升級成功？