Added support for Symfony 7 and PHPUnit 10 (#2)

Bumped minimum versions

- API Platform ^2.5 to ^3.0
- PHP ^7.4 to ^8.1
- Symfony ^5.2 to ^6.0

Added support for Symfony 6

Moved registration of ApiPlatformListeners to a separate registrator …

…class

Added first implementation of event listeners for API Platform