Return pdf_data localized to the order's locale (Z#131360)

src/pretix/api/serializers/order.py

@@ -12,6 +12,7 @@ from rest_framework.reverse import reverse
 
 from pretix.api.serializers.i18n import I18nAwareModelSerializer
 from pretix.base.channels import get_all_sales_channels
+from pretix.base.i18n import language
 from pretix.base.models import (
     Checkin, Invoice, InvoiceAddress, InvoiceLine, Order, OrderPosition,
     Question, QuestionAnswer,
@@ -140,6 +141,7 @@ class PdfDataSerializer(serializers.Field):
         res = {}
 
         ev = instance.subevent or instance.order.event
+        with language(instance.order.locale):
             # This needs to have some extra performance improvements to avoid creating hundreds of queries when
             # we serialize a list.