[Checkins] [zopefoundation/zope.exceptions] 8b6a28: tox.ini: use extras, use python3 for docs

[Marius Gedminas]

  Branch: refs/heads/tox-refresh
  Home:   https://github.com/zopefoundation/zope.exceptions
  Commit: 8b6a2822ea1fe28274b901bd5b05bd82dff75597
      https://github.com/zopefoundation/zope.exceptions/commit/8b6a2822ea1fe28274b901bd5b05bd82dff75597
  Author: Marius Gedminas <marius at gedmin.as>
  Date:   2020-04-10 (Fri, 10 Apr 2020)

  Changed paths:
    M tox.ini

  Log Message:
  -----------
  tox.ini: use extras, use python3 for docs

We still need to use Python 2 for coverage because we have a bunch of
Python-2-only fallback paths in exceptionformatter.py.