[Checkins] [zopefoundation/zope.paste] f96a71: Add missing install step to Travis config

[Marius Gedminas]

  Branch: refs/heads/fix-supported-py-versions
  Home:   https://github.com/zopefoundation/zope.paste
  Commit: f96a717ead94c1f0cb5eb8a6d541aeb31f502fe6
      https://github.com/zopefoundation/zope.paste/commit/f96a717ead94c1f0cb5eb8a6d541aeb31f502fe6
  Author: Marius Gedminas <marius at gedmin.as>
  Date:   2019-04-25 (Thu, 25 Apr 2019)

  Changed paths:
    M .travis.yml

  Log Message:
  -----------
  Add missing install step to Travis config