Update black command to use preview mode

Author: congminh1254

tox.ini

@@ -41,12 +41,12 @@ deps =
 
 [testenv:format]
 commands =
-    black --skip-string-normalization .
+    black --preview --skip-string-normalization .
 deps = black
 
 [testenv:format-check]
 commands =
-    black --skip-string-normalization --check .
+    black --preview --skip-string-normalization --check .
 deps = black