As linting warnings is included in the test suite, if introducing new
rules is not controlled, the suite will keep breaking upon new rules.

We don't usually use TargetRubyVersion in other extensions:
- https://github.com/solidusio/solidus_auth_devise/blob/4a4f9f213d45b77cead29f45bf5bfd0d2021ab46/.rubocop.yml
- https://github.com/solidusio/solidus_stripe/blob/993a43db00ae15984e505a6a4641db955c0eaf1b/.rubocop.yml

Also, this was causing a lint warning as the version did not match the
minimum Ruby version listed in the gemspec. TargetRubyVersion can't be
2.5 as it's not supported by Rubocop, and thus Rubocop shouldn't ditact
the gem's required version.

Due to the following PR, the Country factory no longer always returns
true for `states_required`. It can be true for the appropriate countries
that require a state in shipping addresses. Because of this, addresses
using a country where `states_required` is true, such as the US, need
a state in the Spree::Address record to be valid.
solidusio/solidus#4272

Cardinal, that handles "3D Secure" for Braintree made some changes to
how the legacy 3Ds test numbers are handled. Because of this, the
numbers were changed to trigger the correct scenarios needed. The
DOM of the Cardinal iFrame also changed and needed tweaking. Cardinal
also likes the expiration date to be January and 3 years ahead of
today's year.

References:
- https://cardinaldocs.atlassian.net/wiki/spaces/CCen/pages/400654355/3DS+1.0+Test+Cases
- https://cardinaldocs.atlassian.net/wiki/spaces/CCen/pages/903577725/EMV+3DS+Test+Cases#Test-Case-12%3A-Error-on-Authentication