Feature Request: Add self upgrade option for atuin cli about atuin

[ellie]

We have it with 18.3!

If you use the installer listed here: https://github.com/atuinsh/atuin/releases/tag/v18.3.0

You'll have atuin-update alongside atuin, which will perform the update.

Currently our installer will use the system package manager where available (and this installer where it isn't), however once we've confirmed that the new script works as expected across platforms then it will become the default behaviour

[mjcc30]

Ok sorry my bad, i was on 18.2
just change to script install and it works perfectly!
thank you !