What

In the contribution document it's recommended to use PSR-2, which is deprecated.

How

Switch to PSR-12, which is current PHP standard and used by most open source PHP projects.

• add PHP code style fixer and default rules to the root project dir to easily detect code style violations
• add a composer script to easily run the code style fixer
• add a git hook which checks the code style

If you are okay with that idea, I'll like to support Codeception again and will prepare a pull request. 👋