[TELE-694] fix "JSON object must be str, not 'bytes'"

passerelle_imio_extra_fees/models.py

@@ -58,7 +58,7 @@ class ExtraFees(BaseResource):
     def default_compute(self, request, **kwargs):
         nb_documents = 0
         nb_letter = 0
-        data = json_loads(request.body.decode('utf-8'))
+        data = json_loads(request.body)
         postage_fee = Decimal(self.belgium_postage_fee)
         for basket_item in data['data']:
             try: