Bug 7468: fix the export labels popup header

Bug 7468: fix the export labels popup header

When exporting a barcode range, the export popup should display "1 batch
to export" instead of "0 batches to export". In this context, it can be
considered a label batch and should be counted as such.

To test:
When clicking the "Print range" button, the popup should show "1 batch
to export".

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>