fix(package): update prettier to version 2.0.3

Closes #109

Author: greenkeeper[bot]

package.json

@@ -69,7 +69,7 @@
     "jest-runner-tsc": "^1.6.0",
     "jest-watch-typeahead": "^0.4.2",
     "lodash": "^4.17.15",
-    "prettier": "1.19.1",
+    "prettier": "2.0.3",
     "typescript": "^3.7.3",
     "yargs": "^15.0.2"
   },