chore(package): update prettier to version 2.0.4

Closes #34

Author: greenkeeper[bot]

package.json

@@ -52,7 +52,7 @@
     "eslint-plugin-prettier": "^2.6.2",
     "mocha": "^6.0.0",
     "nyc": "^12.0.2",
-    "prettier": "^1.14.0",
+    "prettier": "^2.0.4",
     "rimraf": "^2.6.1"
   },
   "dependencies": {}