Update prettier to the latest version 🚀 (#5164)

* chore(package): update prettier to version 1.15.0

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]

package-lock.json

@@ -68,7 +68,7 @@
     "mongodb-runner": "4.3.2",
     "nodemon": "1.18.4",
     "nyc": "^12.0.2",
-    "prettier": "1.14.3",
+    "prettier": "1.15.0",
     "supports-color": "^5.4.0"
   },
   "scripts": {