Update pytest to 3.6.0 (#3572)

* Update pytest from 3.5.1 to 3.6.0
* Add new atomicwrites dependency
* Ignore deprecation warnings triggered by pytest-django

requirements/dev.txt

@@ -1,8 +1,8 @@
 # Dependencies needed only for development/testing.
 
-pytest==3.5.1 \
-    --hash=sha256:829230122facf05a5f81a6d4dfe6454a04978ea3746853b2b84567ecf8e5c526 \
-    --hash=sha256:54713b26c97538db6ff0703a12b19aeaeb60b5e599de542e7fca0ec83b9038e8
+pytest==3.6.0 \
+    --hash=sha256:c76e93f3145a44812955e8d46cdd302d8a45fbfc7bf22be24fe231f9d8d8853a \
+    --hash=sha256:39555d023af3200d004d09e51b4dd9fdd828baa863cded3fd6ba2f29f757ae2d
 
 django-debug-toolbar==1.9.1 \
     --hash=sha256:4af2a4e1e932dadbda197b18585962d4fc20172b4e5a479490bc659fe998864d \
@@ -41,6 +41,7 @@ isort==4.3.4 \
     --hash=sha256:b9c40e9750f3d77e6e4d441d8b0266cf555e7cdabdcff33c4fd06366ca761ef8
 
 # Required by pytest
+atomicwrites==1.1.5 --hash=sha256:a24da68318b08ac9c9c45029f4a10371ab5b20e4226738e150e6e7c571630ae6
 attrs==18.1.0 \
     --hash=sha256:4b90b09eeeb9b88c35bc642cbac057e45a5fd85367b985bd2809c62b7b939265 \
     --hash=sha256:e0d0eb91441a3b53dab4d9b743eafc1ac44476296a2053b6ca3af0b139faf87b

setup.cfg

@@ -47,6 +47,8 @@ filterwarnings =
     ignore:sys.exc_clear\(\) not supported in 3.x; use except clauses:DeprecationWarning
     ignore:classic int division:DeprecationWarning:django.db.backends.base.schema
     ignore:In 3.x, reload\(\) is renamed to imp.reload\(\):DeprecationWarning:django.db.migrations.loader
+    # https://github.com/pytest-dev/pytest-django/issues/596
+    ignore:MarkInfo objects are deprecated:DeprecationWarning:pytest_django.plugin
 markers =
     slow: mark a test as slow.
 xfail_strict = true