Merge pull request #96 from mozilla-services/pyup-update-pytest-3.5.1-to-3.6.0

Update pytest to 3.6.0

Author: stephendonner

axe_selenium_python/tests/requirements/tests.txt

@@ -1,4 +1,4 @@
-pytest==3.5.1
+pytest==3.6.0
 selenium==3.12.0
 pytest-selenium==1.13.0
 pytest-html==1.17.0