Update PHP version

[rodber]

This one adds support for PHP 7.4, PHP 8.0 and PHP 8.1. By the way, I would like to know what is required to get to a stable release for this package and I will help in anything needed.

🤗 Hope it helps.

P.S. Thanks to this I made this: chevere/xr so thank you very much!

[SimonFrings]

@rodber Thanks for looking into this, definitely something that needs to be done 👍

There are a lot of different topics addressed in one pull request. It would make more sense to split them into separate ones:

1. Updating to the new ReactPHP API (default-loop, HttpServer, SocketServer)
2. Adding the new PHP versions in addition with supporting the current version of PHPUnit

Regarding 1:
I did some similar work a while back after the new default loop was introduced. You can take a look at clue/reactphp-redis#114 for more details concerning the default loop.

Regarding 2:
I also updated all the ReactPHP projects to the current PHPUnit versions. It is also possible to support old and new versions with some workarounds we used. Take a look at reactphp/http#364, reactphp/http#393 and reactphp/http#402 for the workarounds and the new files for PHPUnit and GitHub actions.

This project is currently more of a proof of concept to show how Server-Sent Events (SSE) can be used with @reactphp. We're working on a more permanent solution for Framework X in the near future.

If there's anything I can help with feel free to ask 👍