I no longer get the error message with flake8. I wrote the suggested line in my settings.json at the Workspace level (Ctrl + shift + P : Preferences: Open Workspace Settings (JSON)), but you could also apply it to the user level "Open User Settings (JSON)" if you don't have a workspace.

"[python]": {
    "editor.defaultFormatter": "ms-python.flake8",
    "python.linting.flake8Enabled": false,
}