Keeping the list of ISO 3166-2 up-to-date requires some maintenance. At
the same time, PHP ISO Codes maintains an up-to-date database with even
more ISO codes we could use in this library.
This change doesn't fully use all resources of PHP ISO Codes, but it
already removes some unnecessary code from the repository.
We've already used this library, but it was heavy because it included
all the localizations in it. Now, the package is much smaller (5.0M).
Signed-off-by: Henrique Moody <henriquemoody@gmail.com>
