Merge branch 'fix/use-correct-object-404' into 'master'

Use DRF's get_object_or_404 instead of the default in the pizzas viewset

See merge request !628

website/pizzas/api/viewsets.py

-from django.shortcuts import get_object_or_404
 from django.db import IntegrityError
 
 from rest_framework import permissions
+from rest_framework.generics import get_object_or_404
 from rest_framework.viewsets import GenericViewSet, ModelViewSet
 from rest_framework.mixins import ListModelMixin
 from rest_framework.decorators import list_route