nushell: use version.(major|minor|patch) if available

[poliorcetics]

I added (version).major and others like it in nushell/nushell#12561 to make atuin's life easier regarding version parsing.

At the moment we obviously have to keep the support for older versions but in a year (or more?) we will be able to reasonably just use the new members I think and make that part of the script much cleaner 🤞

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

[ellie]

Nice! Thank you!

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