[Checkins] [zopefoundation/transaction] 0b8e63: xenial is now the default

[Michael Howitz]

  Branch: refs/heads/icemac-patch-1
  Home:   https://github.com/zopefoundation/transaction
  Commit: 0b8e63f60c185a69b54c7593d1b291da5075e425
      https://github.com/zopefoundation/transaction/commit/0b8e63f60c185a69b54c7593d1b291da5075e425
  Author: Michael Howitz <mh at gocept.com>
  Date:   2019-05-06 (Mon, 06 May 2019)

  Changed paths:
    M .travis.yml

  Log Message:
  -----------
  xenial is now the default 

See https://blog.travis-ci.com/2019-04-15-xenial-default-build-environment