Add GitHub Actions workflow for PHP Composer

[leeannascarrion420-ux]

Problem this Pull Request solves

How has this been tested

Checklist

• I have read the documentation relating to systems affected by this pull request, see https://github.com/eventespresso/event-espresso-core/tree/master/docs
• User input is adequately validated and sanitized
• all publicly displayed strings are internationalized (usually using esc_html__(), see https://codex.wordpress.org/I18n_for_WordPress_Developers)
• My code is tested.
• My code follows the Event Espresso code style.
• My code has proper inline documentation.
• My code accounts for when the site is in Maintenance Mode (MM2 especially disallows usage of models)

[tn3rb]

???

ummm... were you trying to add a GitHub Action to OUR repo? Because that's not going to happen. We already have all of the workflows we want running on this repo, thank you.

You also haven't filled out any of the details in the pull request template explaining what it is you are trying to achieve, so I don't know what problem it is you are trying to solve.

If there is some problem you are experiencing that you thought adding a workflow to our repo would solve, then maybe let me know what that is and I can see if there is anything I can do to help you.

Your workflow won't work anyways because there isn't a composer.json file in this repo to run.