Fix: Assigning the return value of new by reference is deprecated

htdocs/compta/export/modules/compta.export.poivre.class.php

htdocs/compta/export/modules/compta.export.safran.class.php

htdocs/expedition/expedition.class.php

htdocs/includes/modules/export/export_excel.modules.php

htdocs/livraison/livraison.class.php

scripts/books/droits-nouveautes.php

scripts/company/export-contacts-xls-example.php