Update apply_sorting and get_queryset methods in adventures/views.py

* Change `apply_sorting` method to reference `start_date` field instead of `date` field
* Remove references to `date` field in `get_queryset` method

backend/server/adventures/views.py

@@ -40,7 +40,7 @@ class AdventureViewSet(viewsets.ModelViewSet):
         order_direction = self.request.query_params.get('order_direction', 'asc')
         include_collections = self.request.query_params.get('include_collections', 'true')
 
-        valid_order_by = ['name', 'type', 'date', 'rating', 'updated_at']
+        valid_order_by = ['name', 'type', 'start_date', 'rating', 'updated_at']
         if order_by not in valid_order_by:
             order_by = 'name'
 
@@ -1052,4 +1052,4 @@ class AdventureImageViewSet(viewsets.ModelViewSet):
         return AdventureImage.objects.filter(user_id=self.request.user)
 
     def perform_create(self, serializer):
-        serializer.save(user_id=self.request.user)
+        serializer.save(user_id=self.request.user)