fix(package): update qs to version 6.9.1

Closes #90

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
     "lodash.pick": "4.4.0",
     "lodash.uniq": "4.5.0",
     "lodash.uniqby": "4.7.0",
-    "qs": "6.5.2",
+    "qs": "6.9.1",
     "request": "2.88.0",
     "use-strict": "1.0.1",
     "uuid": "^3.2.1"