Upgrading to gatsby 4 beta

[rmatambo8]

Hi! In case you didn’t know, Gatsby is planning its next major version for Q4 of this year! In preparation, the Gatsby team is reaching out to maintainers for our most popular Starters to help make the upgrade to Gatsby 4 as smooth as possible.

This PR updates your Gatsby Starter to the beta version of this next release, as well as some related plugins. It’s just in draft form for now, since the 4.0.0 version of Gatsby isn’t quite ready for general release yet. We’re mainly testing updating Gatsby and the other official plugins to ensure that the Starter builds without errors.

Note: Gatsby 4 requires Node v14 or higher. This is a change from Gatsby 3, which worked with Node v12.13 or newer.
Once version 4.0.0 is ready, we'll come back to update the dependencies and convert this draft to a PR for review. Until then, no action is required on your end. If you have any questions / concerns, let us know in the comments.

Thanks again for all your work as a Gatsby maintainer. We’re so grateful to have you as part of our community. 💜

For more information on what’s coming with Gatsby v4, check out the [GitHub Discussion](https://github.com/gatsbyjs/gatsby/discussions/32860](https://github.com/gatsbyjs/gatsby/discussions/32860).

Changes:

• updated package.json dependencies to g4-beta tags
• changed react syntax to preferred syntax

[rmatambo8]

This is a message from GatsbyJS: updating to Gatsby v4 stable release

Hi, we are getting closer to the Gatsby 4 general availability(GA). We reached out to you about Gatsby 4 alpha but didn't get a response from you and so now we're following up.

We have successfully launched a site in Gatsby 4 beta using this starter and here's the link

Since your starter is popular, we want to reach out to you one more time because we haven't received a response from you.

Soon we are going to launch a stable release and would love for your starter to be released on the day Gatsby 4 GA.

Are you still planning to update your starter to Gatsby v4?

P.S. Starters that are not on Gatsby version 4 will no longer be featured on our recommended starters page.

[rmatambo8]

closed in favor of: #6