fix(package): update react-scripts to version 3.4.0

Closes #8

Author: greenkeeper[bot]

package.json

@@ -7,7 +7,7 @@
     "gh-pages": "^2.0.1",
     "react": "^16.8.5",
     "react-dom": "^16.8.5",
-    "react-scripts": "3.0.0"
+    "react-scripts": "3.4.0"
   },
   "scripts": {
     "start": "react-scripts start",