chore(deps): update dependency prettier to ^1.18.0 (#1989)

Author: renovate[bot]

package-lock.json

@@ -95,7 +95,7 @@
     "marked": "^0.6.2",
     "memfs": "^2.15.4",
     "npm-run-all": "^4.1.5",
-    "prettier": "^1.17.1",
+    "prettier": "^1.18.0",
     "puppeteer": "^1.17.0",
     "rimraf": "^2.6.3",
     "standard-version": "^6.0.1",