Add README.md labels

[lotyp]

Description

As we now have mutation testing with the Stryker dashboard, we can enhance our README.md file with several badges to showcase our project's quality metrics.

Tasks

1. Mutation Testing Badge:

   • [ ] Add a badge for mutation testing from the Stryker dashboard.

2. Codecov Badge:

   • [ ] Integrate the Codecov badge to display our code coverage status.

3. Static Analysis Badges:

   • [ ] Add badges for static analysis tools: Psalm and PHPStan.

Benefits

• Improved Readability: These badges will provide at-a-glance information about the project's quality metrics.
• Transparency: Helps contributors and users quickly understand the health of the codebase.
• Encourages Contributions: A well-maintained project with visible metrics can attract more contributions.

References

• Stryker Dashboard Documentation
• Codecov Documentation
• Psalm Documentation
• PHPStan Documentation

Example Projects

https://github.com/wayofdev/php-cs-fixer-config/blob/master/.github/workflows/testing.yml