[fix] add .fr translation directly in code

static/src/js/mail_edit.js

@@ -82,7 +82,7 @@
             var msg_id = $(event.currentTarget).data('message-id');
             Dialog.confirm(
                 self,
-                _t("Do you really want to delete this message?"), {
+                _t("Voulez-vous vraiment effacer ce message ?"), {
                     confirm_callback: function () {
                         return self._rpc({
                             model: 'mail.message',