Update tox from 2.8.1 to 3.0.0 (#470)

pyup.io bot · asvetlov · commit d5b59d88c251 · 2018-05-04T14:13:13.000+03:00
diff --git a/requirements.txt b/requirements.txt
@@ -5,7 +5,7 @@ ipython==6.3.1
 flake8==3.4.1
 -e .[sa]
 sphinx==1.7.4
-tox==2.8.1
+tox==3.0.0
 pytest==3.5.1
 pytest-cov==2.5.1
 pytest-sugar==0.9.0
