PHP8.3 compatibility issues

Problem/Motivation

Fatal error: Declaration of Drupal\jsonapi_schema\Normalizer\::normalize($entity, $format = null, array $context = []) must be compatible with Drupal\jsonapi_schema\Normalizer\DataDefinitionNormalizer::normalize($entity, $format = null, array $context = []): ArrayObject|array|string|int|float|bool|null in /var/www/html/web/modules/contrib/jsonapi_schema/src/Normalizer/ComplexDataDefinitionNormalizer.php

Proposed resolution

Add type of return value.