Fix missing lib

htdocs/compta/sociales/card.php

@@ -29,6 +29,7 @@ require_once DOL_DOCUMENT_ROOT.'/compta/bank/class/account.class.php';
 require_once DOL_DOCUMENT_ROOT.'/compta/sociales/class/chargesociales.class.php';
 require_once DOL_DOCUMENT_ROOT.'/core/class/html.formsocialcontrib.class.php';
 require_once DOL_DOCUMENT_ROOT.'/core/lib/tax.lib.php';
+require_once DOL_DOCUMENT_ROOT.'/core/lib/date.lib.php';
 if (! empty($conf->projet->enabled))
 {
 	require_once DOL_DOCUMENT_ROOT.'/projet/class/project.class.php';