move loading editions to task

fedireads/connectors/abstract_connector.py

@@ -43,6 +43,12 @@ class AbstractConnector(ABC):
         pass
 
 
+    @abstractmethod
+    def expand_book_data(self, book):
+        ''' get more info on a book '''
+        pass
+
+
     @abstractmethod
     def get_or_create_author(self, book_id):
         ''' request and format a book given an identifier '''