Rule: [PSR-3](https://www.php-fig.org/psr/psr-3/) defines the `PSR\Log\LoggerInterface`, a standard for logging libraries.
Rationale:
All Symfony apps should use the same approach for logging
Rule: PSR-3 must be implemented via [Monolog](https://github.com/Seldaek/monolog)
Rationale:
Monolog is easy to install and use