Add support for Symfony 6.0

[xvilo]

Symfony version 6.0 is freshly released and this library does not yet seem to support this new version. Would be great if somebody could verify it's compatibility and create a new release 👍

Currently don't have the time to do it myself, but maybe we'll be there sometime. For now creating this issue to keep track of the problem

[m-bymike]

Hi, thank you for creating the ticket. It's the same problem for me at the moment, time's limited...