chore(package): update prettier to version 2.0.4

Closes #140

Author: greenkeeper[bot]

package.json

@@ -70,7 +70,7 @@
     "postcss-custom-properties": "7.0.0",
     "postcss-discard-comments": "^4.0.1",
     "postcss-each": "^0.10.0",
-    "prettier": "^1.16.1",
+    "prettier": "^2.0.4",
     "react": "^16.7.0",
     "react-dom": "^16.7.0",
     "react-test-renderer": "^16.7.0",