Changes in monolog/monolog:

• Remove deprecated https://github.com/Seldaek/monolog/blob/2e97231b969e0ffdeff03329b808945b4ba55e38/src/Monolog/Formatter/MongoDBFormatter.php#L157 
• Use Client::getCollection instead of selectCollection
  https://github.com/Seldaek/monolog/blob/2e97231b969e0ffdeff03329b808945b4ba55e38/src/Monolog/Handler/MongoDBHandler.php#L53 

Changes in symfony/monolog-bundle:

• Add monolog formatter service and use it by default with the monolog handler: https://github.com/symfony/monolog-bundle/pull/326 
• Rename "mongo" to "mongodb" by using a deprecation in 3.x
  https://github.com/symfony/monolog-bundle/blob/c64ef750c81125edbf9c2198f87d5743e544c9f3/src/DependencyInjection/MonologExtension.php#L253-L279 

This needs to be done before the release v4.x of the bundle (in November 2025).