Restore Symfony 6.4 compatibility or add support for doctrine/event-manager:^2 in a v6.0.2

Hi,

It would be very welcome to restore Symfony 6.4 compatibility. Symfony 7.0 is 6.4 with deprecated removed, so there was no reason in the first place to remove its support and force people to upgrade both Symfony and this lib at the same time.

Plus, and that's the main issue, this lib prevents from upgrading to doctrine/event-manager:^2 with Symfony 6.4, so it prevents from upgrading to Sylius ^2, which requires doctrine/event-manager:^2, without upgrading to Symfony 7. Not everyone want to upgrade to Symfony 7 right away, some want to remain on LTS versions, and it's a lot more work to upgrade to Symfony 7.

Making a v6.0.2 adding support for doctrine/event-manager:^2 would also solve this issue.

No files or tests are named. Start by locating the package dependency constraints and compatibility checks, then verify installation with Symfony 6.4 and doctrine/event-manager:^2; done means the supported combination works and a v6.0.2 release is prepared.

Written by the indexing model from the issue text.