chore(package): update should to version 12.0.0

Author: greenkeeper[bot]

package.json

@@ -31,6 +31,6 @@
     "istanbul": "^0.4.2",
     "mocha": "^3.5.0",
     "mongoose": "^4.11",
-    "should": "^11.1.2"
+    "should": "^12.0.0"
   }
 }