Fix usages of Symfony\Component\Form\Extension\Core\ChoiceList

[aivus]

Symfony\Component\Form\Extension\Core\ChoiceList deprecated since 2.7. Removed in 3.0

SHFormBundle/Form/Core/DataTransformer/ChoiceToJsonTransformer.php

Line 16 in e1fae05

use Symfony\Component\Form\Extension\Core\ChoiceList\ChoiceListInterface;