Set min required tox to 3.16.1
Set min required tox to 3.16.1

This change enxures that `{temp_dir}` substitution actually works.

Refs:
* https://github.com/tox-dev/tox/issues/1608
* https://github.com/tox-dev/tox/pull/1609
* https://github.com/tox-dev/tox/pull/1610

willthames/ansible-lint