fix: record negative exit codes

[stevenxxiu]

Without the = I get the error on pressing Ctrl + C:

error: Found argument '-1' which wasn't expected, or isn't valid in this context

  If you tried to supply '-1' as a value rather than a flag, use '-- -1'

Usage: atuin history end --exit <EXIT> <ID>

For more information try '--help'

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Name	Status	Preview	Comments	Updated
atuin	✅ Ready (Inspect)	Visit Preview	💬 Add your feedback	Mar 27, 2023 at 1:36PM (UTC)

[ellie]

Nice catch! Thanks