[Checkins] [zopefoundation/Zope] 2ad74a: Use DocumentTemplate branch 3.x.

[Maurits van Rees]

  Branch: refs/heads/maurits/zope-4x-documenttemplate-3x
  Home:   https://github.com/zopefoundation/Zope
  Commit: 2ad74a06f98535ef5d8500ecf674d6d2294a3cca
      https://github.com/zopefoundation/Zope/commit/2ad74a06f98535ef5d8500ecf674d6d2294a3cca
  Author: Maurits van Rees <maurits at vanrees.org>
  Date:   2020-09-17 (Thu, 17 Sep 2020)

  Changed paths:
    M sources.cfg

  Log Message:
  -----------
  Use DocumentTemplate branch 3.x.

The master branch targets Zope 5.
It fails with python 2.7:

```
File "/Users/maurits/community/plone-coredev/5.2/src/DocumentTemplate/src/DocumentTemplate/DT_Var.py", line 156, in <module>
    import urllib.parse
ImportError: No module named parse
```