Update tox from 3.14.1 to 3.14.3 (#59)

Author: pyup-bot

requirements_dev.txt

@@ -18,4 +18,4 @@ pytest==5.3.2
 pytest-asyncio==0.10.0
 pytest-runner==5.2
 pytest-cov==2.8.1
-tox==3.14.1
+tox==3.14.3