Merge pull request #97 from mozilla-services/pyup-update-pytest-selenium-1.12.0-to-1.13.0

Update pytest-selenium to 1.13.0

Author: stephendonner

axe_selenium_python/tests/requirements/tests.txt

@@ -1,5 +1,5 @@
 pytest==3.5.1
 selenium==3.12.0
-pytest-selenium==1.12.0
+pytest-selenium==1.13.0
 pytest-html==1.17.0
 pytest_base_url==1.4.1