Symfony 6 compatibility

[metaer]

No description provided.

[tacman]

I made some of the easy changes for Symfony 6 support, mostly fixing the method signatures to include typehints.

But I'm not sure how to set up the database for testing. I'm getting a failure when running phpunit that is almost certainly related to my testing environment and not some issue in the code, which I think will be pretty easy to make compatible with Symfony 6.

[theofidry]

Fixed with the new release