chore(deps): update dependency prettier to v1.9.0

Author: renovate[bot]

package.json

@@ -78,7 +78,7 @@
     "lerna": "2.5.1",
     "lint-staged": "6.0.0",
     "pre-commit": "1.2.2",
-    "prettier": "1.8.2",
+    "prettier": "1.9.0",
     "ts-jest": "20.0.14",
     "typescript": "2.5.2"
   }