Update react component lifecycle methods

[arathjz]

This method has to be updated to ComponentDidMount:

componentWillMount() {
      const { containerElement, mapElement } = this.props
      invariant(
        !!containerElement && !!mapElement,
        `Required props containerElement or mapElement is missing. You need to provide both of them.
 The \`google.maps.Map\` instance will be initialized on mapElement and it's wrapped by\
 containerElement.\nYou need to provide both of them since Google Map requires the DOM to\
 have height when initialized.`
      )
    }

[JustFly1984]

@arathjz The repo of this project is unmaintained more than a year, and we had build new version https://www.npmjs.com/package/@react-google-maps/api

We had rewrite it to TypeScript, and updating it frequently: https://github.com/JustFly1984/react-google-maps-api/tree/master/packages/react-google-maps-api You can enjoy autocomplete.

You can see our docs: https://react-google-maps-api-docs.netlify.com/

Also a lot of examples: https://react-google-maps-api-gatsby-demo.netlify.com/ https://github.com/JustFly1984/react-google-maps-api/tree/master/packages/react-google-maps-api-gatsby-example/src/examples

The bundle size is much smaller: https://bundlephobia.com/result?p=@react-google-maps/api

Our Spectrum community: https://spectrum.chat/react-google-maps
Our Slack channel: https://join.slack.com/t/react-google-maps-api/shared_invite/enQtODc5ODU1NTY5MzQ4LTBiNTYzZmY1YmVjYzJhZThkMGU0YzUwZjJkNGJmYjk4YjQyYjZhMDk2YThlZGEzNDc0M2RhNjBmMWE4ZTJiMjQ

Enjoy!