Workflow: add action to automaically create a github release

[LvckyAPI]

All Submissions:

• Have you followed the MainWP Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

I've added a GitHub Action, which is reading the stable tag from readme.txt and set a GitHub Release Tag automatically, if the same tag isn't already existing.

Closes #666

How to test the changes in this Pull Request:

1. See in my forked repo, it worked

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• [~] Have you written new tests for your changes, as applicable?
• [~] Have you successfully run tests with your changes locally?

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[LvckyAPI]

@bogdan-mainwp