fix typos in dp_shipping_service.py

models/dp_shipping_service.py

@@ -22,6 +22,6 @@ class SMCShippingDpService(models.Model):
 
 # extend stock.picking with fields for Shipment and Voucher ID
 class SMCStockPickingDp(models.Model):
-    _inerit = "stock.picking"
-    dp_shipping_number = fields.Char(string="DP Shipment ID")
+    _inherit = "stock.picking"
+    dp_shipment_number = fields.Char(string="DP Shipment ID")
     dp_voucher_number = fields.Char(string="DP Voucher ID")