style: make black happy

Author: alvarolopez

caso/extract/openstack/cinder.py

@@ -53,7 +53,7 @@ def _build_record(self, volume, extract_from, extract_to):
         if vol_created < extract_from:
             vol_created = extract_from
 
-        active_duration_delta = (extract_to - vol_created)
+        active_duration_delta = extract_to - vol_created
         ms = active_duration_delta.microseconds
         td = datetime.timedelta(microseconds=ms)
         active_duration = (active_duration_delta - td).total_seconds()