[Checkins] [zopefoundation/z3c.form] e7e0be: Drop Python 3.4 support. Add 3.7 and 3.8 support.

[Maurits van Rees]

  Branch: refs/heads/maurits/3x-update-python-versions
  Home:   https://github.com/zopefoundation/z3c.form
  Commit: e7e0be2a7bf170267f0640bafd5140b4009259fe
      https://github.com/zopefoundation/z3c.form/commit/e7e0be2a7bf170267f0640bafd5140b4009259fe
  Author: Maurits van Rees <maurits at vanrees.org>
  Date:   2020-08-28 (Fri, 28 Aug 2020)

  Changed paths:
    M .travis.yml
    M CHANGES.txt
    M setup.py
    M tox.ini

  Log Message:
  -----------
  Drop Python 3.4 support.  Add 3.7 and 3.8 support.

Same as current master.

Note that Plone will keep using 3.x for the foreseeable future, because we want the subobject support.