[requires.io] dependency update

Author: requires

requirements.txt

@@ -39,7 +39,7 @@ requirements-detector==0.6
 restructuredtext-lint==1.2.1
 scandir==1.9.0
 setoptconf==0.2.0
-six==1.11.0
+six==1.12.0
 unidiff==0.5.5
 uritemplate.py==3.0.2
 Werkzeug==0.14.1         # via flask