chore(package): update sinon to version 4.1.6

Closes #427

Author: greenkeeper[bot]

package.json

@@ -105,7 +105,7 @@
   },
   "devDependencies": {
     "nodemon": "1.14.3",
-    "sinon": "4.1.3",
+    "sinon": "4.1.6",
     "xo": "^0.18.2"
   }
 }