feat: version command check update

[janoshrubos]

PR Checklist

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• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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• Tests for the changes are included.

What is the current behavior?

ns --version command prints out only the current version of the cli.

What is the new behavior?

ns --version command prints out the current version and the latest available version of the cli with an instruction for update.