Loosen six version requirement

Geeber · web-flow · commit 9f0f9434b0ac · 2018-11-28T11:25:41.000-08:00
See comments on keenlabs#149.
diff --git a/requirements.txt b/requirements.txt
@@ -1,3 +1,3 @@
 pycryptodome>=3.4
 requests>=2.5,<3.0
-six~=1.10.0
+six~=1.10
