update pytest config (#4463)

* update pytest config

pytest 3.8.0 was just released and officially deprecates some of the way
we do pytest marks. They introduced a new way to do this in 3.6 so this
PR switches to that mechanism and updates our minimum pytest requirement

* update the stubs

* also update wycheproof test config to remove deprecated paths

* don't need this any more
diff --git a/setup.py b/setup.py
index 8bd31bd..0c793e3 100644
--- a/setup.py
+++ b/setup.py
@@ -54,7 +54,7 @@
         )
 
 test_requirements = [
-    "pytest>=3.2.1,!=3.3.0",
+    "pytest>=3.6.0",
     "pretend",
     "iso8601",
     "pytz",