Why does parameter 'props' implicitly has an 'any' type?

You should always declare your props and state objects with generics on the Component class. Restrain from using the any keyword whenever possible.

Tip: A modern IDE allows you to F12 and inspect the definition file, that is a great help if your new to TypeScript. You can also read the React definition on the DT GitHub repo, the React.Component are defined here

type AppProps = {}
type AppState = {}
class App extends React.Component<AppProps, AppState> {
    constructor(props: AppProps) {
        super(props);
        //this.props will already be of type AppProps. 
        //Only the constructor props are any
    }

    public render() {
        return (
            <div className="App">
                <h1>Go Type React</h1>
            </div>
        );
    }
}