Fix black formatting

Change coming due to the recent black release

Author: amureki

joeflow/contrib/reversion.py

@@ -43,7 +43,6 @@ def dispatch(self, request, *args, **kwargs):
                 reversion.set_comment(self.name)
             return super().dispatch(request, *args, **kwargs)
 
-
 except ImportError:
 
     class RevisionMixin: