[requires.io] dependency update

requires · requires · commit f1a9b38b6f9d · 2021-04-25T15:26:36.000-07:00
diff --git a/tox.ini b/tox.ini
@@ -93,7 +93,7 @@ basepython = {[default]basepython}
 skip_install = True
 
 deps =
-    black==20.8b1
+    black==21.4b0
 
 setenv =
     BLACK_LINT_ARGS=--check
