fix: Order Post route view (#6683)

Author: prateekj117

app/api/schema/orders.py

@@ -117,7 +117,7 @@ def initial_values(self, data):
                          type_="event")
 
     event_invoice = Relationship(attribute='invoice',
-                                 self_view='v1.order_invoice',
+                                 self_view='v1.order_event_invoice',
                                  self_view_kwargs={'order_identifier': '<identifier>'},
                                  related_view='v1.event_invoice_detail',
                                  related_view_kwargs={'id': '<id>'},