fix test dependencies
fix test dependencies

Test data fixtures have been moved to the xabbuh/xapi-data-fixtures
package. Therefore, we need to depend on this package for tests.

php-xapi/xapi,xabbuh/xapi-validator,xabbuh/xapi-model,xabbuh/xapi-serializer,xabbuh/xapi,php-xapi/serializer,php-xapi/model