[Checkins] [zopefoundation/persistent] 25025c: Move Python 3.9 to jobs.

[Michael Howitz]

  Branch: refs/heads/py39
  Home:   https://github.com/zopefoundation/persistent
  Commit: 25025c9978657c6ab77be93ea4396614c2971786
      https://github.com/zopefoundation/persistent/commit/25025c9978657c6ab77be93ea4396614c2971786
  Author: Michael Howitz <mh at gocept.com>
  Date:   2020-02-12 (Wed, 12 Feb 2020)

  Changed paths:
    M .travis.yml

  Log Message:
  -----------
  Move Python 3.9 to jobs.

It is not found in `matrix`.