chore(deps): update dependency prettier to ^1.19.1 (#2307)

Author: renovate[bot]

package-lock.json

@@ -101,7 +101,7 @@
     "marked": "^0.7.0",
     "memfs": "^2.16.1",
     "npm-run-all": "^4.1.5",
-    "prettier": "^1.18.2",
+    "prettier": "^1.19.1",
     "puppeteer": "^1.20.0",
     "rimraf": "^3.0.0",
     "standard-version": "^7.0.1",