Upgrade create-react-app in examples

[coderkevin]

The current version of create-react-app has a security vulnerability. This is only used in the examples, so the exposure is very limited. But still, this should be addressed.

SEMVER WARNING: Recommended action is a potentially breaking change
┌───────────────┬──────────────────────────────────────────────────────────────┐
│ High          │ Missing Origin Validation                                    │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Package       │ webpack-dev-server                                           │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Dependency of │ react-scripts [dev]                                          │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Path          │ react-scripts > webpack-dev-server                           │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ More info     │ https://nodesecurity.io/advisories/725                       │
└───────────────┴──────────────────────────────────────────────────────────────┘