Remove optional ? in PT zip_regex

[AndreaSmith053122]

What are you trying to accomplish?

Portugal postal code format should be XXXX-XXX, all numeric. Our current regex does not require the second set of three digits, despite it being the required format since 1998.

Contributes to https://github.com/shop/issues-checkout/issues/11587

What approach did you choose and why?

• Remove the ? part of the regex making the second set of digits optional.
• Leave the ? that makes the - optional.

What should reviewers focus on?

I don't think there's any way to flag these changes for a gradual rollout, but I'd be happy to hear otherwise.

The impact of these changes

[After services start using the new gem version]

• Customers will be required to enter the full postal code
• Merchants touching old records will need to put in the full postal code. We expect Atlas to be able to provide the correct value.

Checklist

• I have added a CHANGELOG entry for this change (or determined that it isn't needed)