Bug 1333079 - Update pytest-django from 3.0.0 to 3.1.2

https://pytest-django.readthedocs.io/en/latest/changelog.html
pytest-dev/pytest-django@3.0.0...3.1.2

requirements/dev.txt

@@ -43,4 +43,4 @@ mccabe==0.5.3 --hash=sha256:f9b58bf366c1506dcd6117b33e5c4874746f0de859c9c7cab8b5
 pycodestyle==2.2.0 --hash=sha256:60c4e1c36f301ac539a550a29e9d16862069ec240472d86e5e71c4fc645829cb
 pyflakes==1.3.0 --hash=sha256:ad89dafee8ca32282116209a0ca4dff050bdc343af958721d5517d242c1215d5
 
-pytest-django==3.0.0 --hash=sha256:5952283b0e6e0f9d8cb46803636e3940e1c77da8a529f03a8a4320f52d9bf560
+pytest-django==3.1.2 --hash=sha256:00995c2999b884a38ae9cd30a8c00ed32b3d38c1041250ea84caf18085589662