v3.4.0

• Deprecate "excluded_404s" option
• Flush loggers on kernel.reset
• Register processors (ProcessorInterface) for autoconfiguration (tag: monolog.processor)
• Expose configuration for the ConsoleHandler
• Fixed psr-3 processing being applied to all handlers, only leaf ones are now processing
• Fixed regression when app channel is defined explicitly
• Fixed handlers marked as nested not being ignored properly from the stack
• Added support for Redis configuration
• Drop support for Symfony < 3