updated "devDependencies" to fix vulnerability alerts

Author: unclechu

package.json

@@ -53,8 +53,8 @@
  "test": "./node_modules/.bin/mocha"
  },
  "devDependencies": {
- "mocha": "2.2.1",
- "should": "5.2.0"
+ "mocha": "5.2.0",
+ "should": "13.2.1"
  },
  "files": [
  "index.js",