attempt to use current timezone when checking api key expiry

the `collectoss github api-keys` CLI output shows the key expiry time, but it defaults to using UTC. Having it be shown in local time would make it more helpful for people who regularly use it.

Start with the `collectoss github api-keys` CLI command and trace where it formats the key expiry time. Update the displayed expiry to use the user's local timezone rather than UTC, then verify the command output shows the expected local time.

Written by the indexing model from the issue text.