[requires.io] dependency update

requires · requires · commit 534628749733 · 2021-07-16T07:58:40.000-07:00
diff --git a/tox.ini b/tox.ini
@@ -93,7 +93,7 @@ basepython = {[default]basepython}
 skip_install = True
 
 deps =
-    black==21.6b0
+    black==21.7b0
 
 setenv =
     BLACK_LINT_ARGS=--check
