Update repo to use react 18 by default

[AirballClaytonCalvin]

Is there a plan to update this repo to support React 18 by default?

dash-component-boilerplate/{{cookiecutter.project_shortname}}/package.json

Line 47 in 788d21d

"react": "^16.8.6",

[ndrezn]

For now developers can just change the React 18 version in their projects locally, there's no need to use the version set in the cookiecutter. That being said once the default version of Dash is updated in 3.0 we should also update the recommended version here.