[Checkins] [zopefoundation/Products.PythonScripts] ac9c86: Fix linting issue

[Jürgen Gmach]

  Branch: refs/heads/fix-lint
  Home:   https://github.com/zopefoundation/Products.PythonScripts
  Commit: ac9c86668d11ce416c079ed1d0e8655a25cad6fb
      https://github.com/zopefoundation/Products.PythonScripts/commit/ac9c86668d11ce416c079ed1d0e8655a25cad6fb
  Author: Jürgen Gmach <juergen.gmach at googlemail.com>
  Date:   2020-05-15 (Fri, 15 May 2020)

  Changed paths:
    M tox.ini

  Log Message:
  -----------
  Fix linting issue

... which arise with the new flake8 version.

`tests` is no longer a valid flake8 param, as it is no top level
directory.

As it is a subfolder of the `src` folder, it gets linted anyway.

modified:   tox.ini