chore(greenkeeper): Update @types/prettier to version 2.0.1.

Closes #82.

Author: greenkeeper[bot]

packages/@opticss/demo-app/package.json

@@ -38,7 +38,7 @@
   "dependencies": {
     "@opticss/simple-template": "^0.6.3",
     "@types/codemirror": "^0.0.74",
-    "@types/prettier": "^1.7.0",
+    "@types/prettier": "^2.0.1",
     "@types/split.js": "^1.3.0",
     "babel-cli": "^6.26.0",
     "codemirror": "^5.15.2",