Add Symfony 8 support

[endelwar]

No description provided.

[what-the-diff]

PR Summary

• Upgrade of CI Workflow
  The automatic testing procedure has been updated to use a newer environment dimension (Ubuntu 24.04 instead of 22.04). This update is targeted at the quality assurance procedure (PHPStan) and test jobs.

• Simplification of PHPStan Configuration
  We've streamlined the PHPStan configuration, removing the matrix for different Symfony versions and setting the PHP version directly to 8.4 for simpler operation and maintenance.

• Support for Symfony 8 Added
  We are now able to support Symfony 8 within the tests. This is enabled by a new configuration file (base_symfony_8.yml).

• Updates to the Change Log
  All updates, including the addition of Symfony 8 support, are now reflected in the CHANGELOG.md file.

• Test Setup Modifications
  The setup within FunctionalTest.php has been revised to include the new Symfony 8 configuration.

• Clean-up of Configuration Files
  Irrelevant information and redundant comments have been removed in our configuration files for Symfony 5, 6, and 7. This cleanup helps maintain the clarity of configuration files.