Merge pull request #345 from fantix/pyup-update-tox-3.2.1-to-3.4.0

Update tox to 3.4.0

Author: wwwjfy

requirements_dev.txt

@@ -14,7 +14,7 @@ quart==0.6.7;python_version>="3.6"
 # tests
 coverage==4.5.1
 flake8==3.5.0
-tox==3.2.1
+tox==3.4.0
 pytest==3.8.1
 pytest-runner==4.2
 pytest-asyncio==0.9.0