[Namepsacing] functions with node_name should not hard code namespace

[blaggacao]

def _ubl_add_party(self, partner, company, node_name, parent_node, ns, version='2.1')
hardcodes cbc here: party = etree.SubElement(parent_node, ns['cac'] + node_name)

instead, pass prefixed node_name and carry the nsmap of #131

[github-actions]

There hasn't been any activity on this issue in the past 6 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
If you want this issue to never become stale, please ask a PSC member to apply the "no stale" label.