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

Closes #4

Author: greenkeeper[bot]

package.json

@@ -5,7 +5,7 @@
   "dependencies": {
     "react": "^16.8.6",
     "react-dom": "^16.8.6",
-    "react-scripts": "3.1.0"
+    "react-scripts": "3.4.0"
   },
   "scripts": {
     "start": "react-scripts start",