GREG-25: Adding namespace versioning

Adding namespace-versioning to API.

The swagger interface has been checked and it still works.

It is now possible to look at at a variable in the request (request.version) to inspect the namespace used.

greg/api/views/person.py

 from django.core.exceptions import ValidationError
 from django_filters import rest_framework as filters
 from drf_spectacular.utils import extend_schema, OpenApiParameter
-from rest_framework import viewsets, status, mixins
+from rest_framework import viewsets, status
 from rest_framework.response import Response
-from rest_framework.viewsets import GenericViewSet
 
 from greg.api.filters import PersonFilter, PersonRoleFilter, PersonIdentityFilter
 from greg.api.pagination import PrimaryKeyCursorPagination
 from greg.api.serializers.person import (
     PersonSerializer,
     PersonRoleSerializer,
-    PersonIdentitySerializer, PersonSummarySerializer,
+    PersonIdentitySerializer,
 )
 from greg.models import Person, PersonRole, PersonIdentity
 
@@ -115,12 +114,3 @@ class PersonIdentityViewSet(viewsets.ModelViewSet):
         return Response(
             serializer.data, status=status.HTTP_201_CREATED, headers=headers
         )
-
-
-
-class PersonSummaryViewSet(mixins.ListModelMixin, GenericViewSet):
-
-    queryset = Person.objects.all().order_by("id")
-    serializer_class = PersonSummarySerializer
-    pagination_class = PrimaryKeyCursorPagination
-