update pytest django version

Author: =

setup.py

@@ -21,7 +21,7 @@
     'mock',
     'pytz',
     'django-filter',
-    'pytest-django==2.9.1',
+    'pytest-django>=3.2.1',
 ] + rest_framework_require
 
 django_version = 'Django>=1.8.0,<2' if sys.version_info[0] < 3 else 'Django>=1.8.0'