fix(package): update react-scripts to version 3.0.0

Closes #4

Author: greenkeeper[bot]

package.json

@@ -6,7 +6,7 @@
     "classnames": "^2.2.6",
     "react": "^16.6.0",
     "react-dom": "^16.6.0",
-    "react-scripts": "2.1.0"
+    "react-scripts": "3.0.0"
   },
   "scripts": {
     "start": "react-scripts start",