Update dependencies in tox.ini

Author: cclauss

tox.ini

@@ -27,7 +27,7 @@ commands = pytest {posargs}
 [testenv:lint]
 deps =
     flake8>=3.8,<4
-    black==21.6b0
+    black
     mypy==0.910
     {[testenv]deps}
 commands =
@@ -48,7 +48,7 @@ commands =
 basepython = python3.9
 deps =
     check-manifest==0.46
-    readme-renderer==29.0
+    readme-renderer
     twine
 allowlist_externals = rm
 commands =