Set plg_quickicon_eosnotify to not protected with the next update.

```
Warning
Plugin Uninstall: Trying to uninstall a core plugin: PLG_EOSNOTIFY
```

See: https://github.com/joomla/joomla-cms/pull/5064

@mbabker I'm not sure what run bevor SQL or script.php Updates. But i think the unprotected setting is easyer and better with a SQL file.