py-test-django: updated to 3.4.7

3.4.7:
Bugfixes
* Fix disabling/handling of unittest methods with pytest 4.2+

3.4.6:
Bugfixes
* django_find_project: add cwd as fallback always

Misc
* Enable tests for Django 2.2 and add classifier
* Disallow pytest 4.2.0 in install_requires

(adam)