chore(package): update prettier to version 1.19.1

Closes #15

Author: greenkeeper[bot]

package.json

@@ -34,7 +34,7 @@
     "mocha-typescript": "1.1.17",
     "mochawesome": "3.1.1",
     "nyc": "13.2.0",
-    "prettier": "1.16.4",
+    "prettier": "1.19.1",
     "rimraf": "2.6.3",
     "source-map-support": "0.5.10",
     "tslint": "5.12.1",