FOLIO driver - start copy numbers with 1, not 0 (#1588)

module/VuFind/src/VuFind/ILS/Driver/Folio.php

@@ -442,7 +442,7 @@ class Folio extends AbstractAPI implements
                     'id' => $bibId,
                     'item_id' => $itemBody->items[$j]->id,
                     'holding_id' => $holding->id,
-                    'number' => count($items),
+                    'number' => count($items) + 1,
                     'barcode' => $item->barcode ?? '',
                     'status' => $item->status->name,
                     'availability' => $item->status->name == 'Available',