Upgrade to newer pytest-django for better Python3.
Upgrade to newer pytest-django for better Python3.

rtfd/readthedocs.org,davidfischer/readthedocs.org,safwanrahman/readthedocs.org,rtfd/readthedocs.org,pombredanne/readthedocs.org,davidfischer/readthedocs.org,davidfischer/readthedocs.org,davidfischer/readthedocs.org,rtfd/readthedocs.org,safwanrahman/readthedocs.org,safwanrahman/readthedocs.org,pombredanne/readthedocs.org,rtfd/readthedocs.org,pombredanne/readthedocs.org,safwanrahman/readthedocs.org