chore(package): update unexpected to version 11.8.1

Closes #73

Author: greenkeeper[bot]

package.json

@@ -23,7 +23,7 @@
     "jsdom": "^11.0.0",
     "mocha": "^4.0.0",
     "sinon": "^4.0.0",
-    "unexpected": "^10.36.0",
+    "unexpected": "^11.8.1",
     "unexpected-sinon": "^10.1.1"
   }
 }