bug version 6.6.0

[MAM84]

bug in new version 6.6.0

error with composer install :

In XliffFileLoader.php line 62:
Invalid resource provided: "/vendor/
knplabs/knp-paginator-bundle/translations/KnpPaginatorBundle.zh_CN.xliff";
Errors: [ERROR 1824] Element '{urn:oasis:names:tc:xliff:document:1.2}file',
attribute 'target-language': 'zh_CN' is not a valid value of the atomic ty
pe 'xs:language'. (in /var/www/v2.extranet.apivia-courtage.vm/ - line 3, co
lumn 0)

[michnovka]

same issue

[aarongerig]

This PR will fix that: #814