[importers] Also speed up koreader imports

vrobbler/apps/scrobbles/models.py

@@ -188,6 +188,7 @@ class KoReaderImport(BaseFileImportMixin):
         return path
 
     sqlite_file = models.FileField(upload_to=get_path, **BNULL)
+    webdav_etag = models.CharField(max_length=255, **BNULL)
 
     def save_sqlite_file_to_self(self, file_path):
         with open(file_path, "rb") as f: