Handles outdated Add with Book type

should be edition.

bookwyrm/models/fields.py

@@ -283,6 +283,8 @@ class TagField(ManyToManyField):
         for link_json in value:
             link = activitypub.Link(**link_json)
             tag_type = link.type if link.type != 'Mention' else 'Person'
+            if tag_type == 'Book':
+                tag_type = 'Edition'
             if tag_type != self.related_model.activity_serializer.type:
                 # tags can contain multiple types
                 continue