* Fixed black hook requiring Py3.6 to installed locally. Will now assume
Py3.6+ in installed.
* Added isort traceback in pre-commit flake8 hook fails
* Updated versions of Black, Prettier and isort
* Keep Flake8 at 3.7.9 due to E402 issue: https://gitlab.com/pycqa/flake8/-/issues/638
* New pyproject config for isort v5 with fixes for Python 2 imports.
* Fixed travis config to run Python 3.6 for lint run. Replaced the
virtualenv with_system_site_packages config with Travis specific Python
config value so lint run doesn't attempt to append with_system_site_packages
to Python 3.6 command.
610a1bb313