4 Un-pin tox version from 3.27.1 and remove tox-pyenv. Testing has
5 demonstrated that tox-pyenv is no longer required to obtain correct
6 Python runtime versions when running tests. Also, removed Python 3.8
7 from the VENV setup where it was being specifically requested.
9 Due to unpinning of the tox version, tox.ini configuration files may
10 need modifying to reflect a change in configuration syntax; where
11 whitelist_externals needs to be replaced with allowlist_externals.