[Checkins] [zopefoundation/zopetoolkit] a623c1: Use a cffi version compatible with Python 3.8a2.

[Michael Howitz]

  Branch: refs/heads/py38
  Home:   https://github.com/zopefoundation/zopetoolkit
  Commit: a623c1a569687253f16f831867ed06e9158d5033
      https://github.com/zopefoundation/zopetoolkit/commit/a623c1a569687253f16f831867ed06e9158d5033
  Author: Michael Howitz <mh at gocept.com>
  Date:   2019-03-19 (Tue, 19 Mar 2019)

  Changed paths:
    M ztk-versions.cfg

  Log Message:
  -----------
  Use a cffi version compatible with Python 3.8a2.