Merge pull request #92 from mozilla-services/pyup-update-pytest-3.5.0-to-3.5.1

Update pytest to 3.5.1

Author: stephendonner

axe_selenium_python/tests/requirements/tests.txt

@@ -1,4 +1,4 @@
-pytest==3.5.0
+pytest==3.5.1
 selenium==3.11.0
 pytest-selenium==1.12.0
 pytest-html==1.17.0