[Checkins] [zopefoundation/ZODB] 29225f: Simplify appveyor.yml.

[Jason Madden]

  Branch: refs/heads/appveyor-mock
  Home:   https://github.com/zopefoundation/ZODB
  Commit: 29225f21135214b3090d94adfa06c8c065e0a6ea
      https://github.com/zopefoundation/ZODB/commit/29225f21135214b3090d94adfa06c8c065e0a6ea
  Author: Jason Madden <jamadden at gmail.com>
  Date:   2020-03-05 (Thu, 05 Mar 2020)

  Changed paths:
    M appveyor.yml

  Log Message:
  -----------
  Simplify appveyor.yml.

Fixes issues with zc.buildout and version pins (https://github.com/zopefoundation/ZODB/pull/295#issuecomment-593805066)