[Checkins] [zopefoundation/Zope] ef53ea: Update to ZCatalog 6.0.

[Michael Howitz]

  Branch: refs/heads/master
  Home:   https://github.com/zopefoundation/Zope
  Commit: ef53ea228d25797ded33be340f2807c389dc4ee6
      https://github.com/zopefoundation/Zope/commit/ef53ea228d25797ded33be340f2807c389dc4ee6
  Author: Michael Howitz <mh at gocept.com>
  Date:   2020-10-08 (Thu, 08 Oct 2020)

  Changed paths:
    M constraints.txt
    M requirements-full.txt
    M versions-prod.cfg

  Log Message:
  -----------
  Update to ZCatalog 6.0.