Check upgrade to React 19

[JonasKellerer]

We currently use React 18 in our example, and also to define the JSX interface.

declare global {
    // eslint-disable-next-line @typescript-eslint/no-namespace
    namespace JSX {
        interface IntrinsicElements {
            'gs-location-filter': DetailedHTMLProps<HTMLAttributes<HTMLElement>, HTMLElement>;
        }
    }
}

The syntax now changed: https://react.dev/blog/2024/04/25/react-19-upgrade-guide#the-jsx-namespace-in-typescript

Now one should use

declare module "react" {
  namespace JSX {
    interface IntrinsicElements {
      "my-element": {
        myElementProps: string;
      };
    }
  }
}

Investigate, If we can use the new syntax, while still being able to use the components in react 18.