pin version of flake8

Author: tomato42

tox.ini

@@ -104,7 +104,7 @@ commands = {envpython} speed.py
 basepython = python3
 deps =
      black==22.3.0
-     flake8
+     flake8==6.1.0
 commands =
          flake8 setup.py speed.py src
          black --check --line-length 79 .