Event edit tests fail due to newer DateTime

[mauritsvanrees]

In coredev 5.2 (and Plone 5.2.10.1) I updated Zope for a security fix, but this included a few other package updates which are pinned in the Zope versions.cfg. DateTime was updated from 4.4 to 4.8. Version 4.7 contains a fix for a possible rounding problem. But that causes a test to fail:

$ bin/test -s Products.ATContentTypes -m test_atevent -t test_edit
...
Error in test test_edit (Products.ATContentTypes.tests.test_atevent.TestSiteATEvent)
Traceback (most recent call last):
  File "/Users/maurits/.pyenv/versions/2.7.18/lib/python2.7/unittest/case.py", line 329, in run
    testMethod()
  File "/Users/maurits/community/plone-coredev/5.2/src/Products.ATContentTypes/Products/ATContentTypes/tests/test_atevent.py", line 76, in test_edit
    self.assertEqual(new.end_date, new.end().asdatetime())
  File "/Users/maurits/community/plone-coredev/5.2/src/Products.ATContentTypes/Products/ATContentTypes/content/event.py", line 283, in _end_date
    return value.asdatetime()
  File "/Users/maurits/community/plone-coredev/5.2/src/DateTime/src/DateTime/DateTime.py", line 1733, in asdatetime
    self._minute, second, microsec, tzinfo)
TypeError: integer argument expected, got float

I am looking at doing a PR for DateTime.
Meanwhile the workaround is to pin DateTime back to say 4.6. Let me do that on 5.2.