chore(package): update prettier to version 2.0.4

Closes #72

Author: greenkeeper[bot]

package.json

@@ -52,7 +52,7 @@
     "husky": "^3.0.5",
     "mocha": "^6.2.0",
     "nyc": "^14.1.1",
-    "prettier": "^1.19.1",
+    "prettier": "^2.0.4",
     "ts-node": "^8.5.4",
     "typescript": "^3.7.2"
   },