YITH WooCommerce PDF Invoice 4.25.0

* New: Support for WooCommerce 5.3
* New: added new option to only display the footer in the last page
* Update: YITH plugin framework
* Fix: field "Natura" for city Livigno
* Dev: added new filters yith_ywpdi_mpdf_footer_in_all_pages and yith_ywpdi_mpdf_footer_in_last_page
* Dev: added new hook yith_ywpi_after_write_mpdf_html_template_pdf

New: added new option to configure the number of digits of the invoice number
New:added new option to show the Credit Note amounts in positive
Update: YITH plugin framework

* New: added new option in the plugin settings to avoid duplication of invoice numbers
* Fix: SSN field was incorrect when generating XML invoice