[17.0][FIX] delivery_roulier: calls to is_roulier()

Author: Tisho99

delivery_roulier/models/delivery_carrier.py

@@ -27,7 +27,7 @@ def _is_roulier(self):
         return "get_label" in available_carrier_actions.get(self.delivery_type, [])
 
     def cancel_shipment(self, pickings):
-        if self._is_roulier:
+        if self._is_roulier():
             pickings._cancel_shipment()
         else:
             return super().cancel_shipment(pickings)
@@ -50,7 +50,7 @@ def rate_shipment(self, order):
         res = super().rate_shipment(order)
         # for roulier carrier, usually getting the price by carrier webservice
         # is usually not available for now. Avoid failure in that case.
-        if not res and self.is_roulier():
+        if not res and self._is_roulier():
             res = {
                 "success": True,
                 "price": 0.0,