Update dependency prettier to v1.19.1

Author: renovate-bot

functions/tokenservice/functions/package.json

@@ -28,7 +28,7 @@
     "eslint-plugin-prettier": "^3.1.0",
     "eslint-plugin-promise": "^4.0.1",
     "mocha": "^6.0.2",
-    "prettier": "1.18.2",
+    "prettier": "1.19.1",
     "supertest": "^4.0.0"
   },
   "engines": {