[Checkins] [zopefoundation/BTrees] 3236f0: Fix Python 3.5 MacOS wheel upload

[Marius Gedminas]

  Branch: refs/heads/fix-macos-wheel-upload
  Home:   https://github.com/zopefoundation/BTrees
  Commit: 3236f03b33417dcf62feb5da5e419eb6a6be900f
      https://github.com/zopefoundation/BTrees/commit/3236f03b33417dcf62feb5da5e419eb6a6be900f
  Author: Marius Gedminas <marius at gedmin.as>
  Date:   2019-11-12 (Tue, 12 Nov 2019)

  Changed paths:
    M .travis.yml

  Log Message:
  -----------
  Fix Python 3.5 MacOS wheel upload

Python 3.5 on Mac OS doesn't support TLS 1.2, which makes twine upload
fail, but we can use system Python 2.7 for twine upload, which works.

Also brings the rest of the Travis CI configuration closer in line to
the rest of the packages updated for
https://github.com/zopefoundation/meta/issues/11