[Composer] Added conflict with symfony/dependency-injection v3.5.7

[mnocon]

Our product (v3.3.x-dev and 4.0.x-dev) fails to install with:

!!  In CheckCircularReferencesPass.php line 67:
!!                                                                                 
!!    Circular reference detected for service "Ibexa\Platform\OAuth2Client\Reposi  
!!    tory\User\PasswordHashService", path: "Ibexa\Platform\OAuth2Client\Reposito  
!!    ry\User\PasswordHashService -> Ibexa\Platform\OAuth2Client\Repository\User\  
!!    PasswordHashService". 

Which seems to come from the latest Symfony release: https://github.com/symfony/symfony/releases/tag/v5.3.7

and has been reported to the issue tracker: symfony/symfony#42791

I've decided to add a conflict for a single version (no ^, ~) because I hope that it will be fixed in 5.3.8 - if not I will change the conflict to a broader one.