Updated react-scripts to 3.4.0

This is because of a breaking dependency in react-dev-utils@10.2.0

Context: facebook/create-react-app#8490

Author: Steve Hobbs

02-Calling-an-API/package.json

@@ -27,7 +27,7 @@
     "react": "^16.8.6",
     "react-dom": "^16.8.6",
     "react-router-dom": "^5.0.0",
-    "react-scripts": "3.3.0",
+    "react-scripts": "^3.4.0",
     "reactstrap": "^8.0.0"
   },
   "devDependencies": {