GitHub Action Integration for Test Automation and Composer Updates

[alissn]

Hi there,

In this pull request, I've implemented a GitHub Action to run tests on push and create a merge request. The tests now cover PHP versions 7.1, 7.2, 7.3, 7.4, 8.0, 8.1, 8.2, and 8.3.

Additionally, I've made changes in the composer.json file to update the PHPUnit version based on the PHP version.

Furthermore, I've performed some clean-up tasks related to PHP versions. The syntax "^7.0" is now used to support all PHP versions from 7.0 to 7.4.