Update pytest-django requirement from <3.5,>=3.4 to >=3.4,<3.6
Update pytest-django requirement from <3.5,>=3.4 to >=3.4,<3.6

Updates the requirements on [pytest-django](https://github.com/pytest-dev/pytest-django) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest-django/releases)
- [Changelog](https://github.com/pytest-dev/pytest-django/blob/master/docs/changelog.rst)
- [Commits](https://github.com/pytest-dev/pytest-django/compare/3.4.0...v3.5.1)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
django-oscar/django-oscar-stores,django-oscar/django-oscar-stores,django-oscar/django-oscar-stores