chore(package): update should to version 9.0.0 (#76)

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -49,7 +49,7 @@
     "mocha": "^2.2.5",
     "nock": "^8.0.0",
     "proxyquire": "^1.7.3",
-    "should": "^8.2.2",
+    "should": "^9.0.0",
     "sinon": "^1.15.4",
     "sinon-as-promised": "^4.0.0"
   }