enh: warning when new release is avaiable

> doing "ku" on terminal display if there's a new version available



Now

```
❯ ku

  ku · see you next time · x.com/iamdothash

❯ ku upgrade
Upgrading v0.7.1 -> v0.8.1
Upgraded to v0.8.1
```

After should be


```
❯ ku
  There's a new version v0.8.1. Current version v0.7.1.
  Do to upgrade automatically
     ku upgrade
  (Then opens TUI)
```
