fix(package): update prettier to version 2.0.3

Closes #23

Author: greenkeeper[bot]

package.json

@@ -38,7 +38,7 @@
     "eslint-plugin-promise": "4.2.1",
     "eslint-plugin-react": "^7.18.3",
     "eslint-plugin-standard": "^4.0.0",
-    "prettier": "^1.17.1",
+    "prettier": "^2.0.3",
     "standard-engine": "^12.0.0"
   },
   "devDependencies": {