Add Laravel/Lumen 9 and Symfony 6 support

[asgrim]

Fixes scoutapp/scout-apm-laravel#83

NOTE: there are BC breaks in this PR, as follows:

 - [BC] Scoutapm\Laravel\Providers\ScoutApmServiceProvider was marked "@internal"
 - [BC] Scoutapm\ScoutApmBundle\Twig\TwigDecorator was marked "@internal"
 - [BC] Scoutapm\ScoutApmBundle\ScoutApmBundle was marked "@internal"
 - [BC] Scoutapm\ScoutApmBundle\DependencyInjection\ScoutApmExtension was marked "@internal"
 - [BC] Symfony\Component\HttpKernel\Event\ControllerEvent was marked "@internal"
 - [BC] Scoutapm\Logger\FilteredLogLevelDecorator was marked "@internal"
 - [BC] The parameter $message of Psr\Log\LoggerTrait#emergency() changed from no type to a non-contravariant string|Stringable
 - [BC] The parameter $message of Psr\Log\LoggerTrait#alert() changed from no type to a non-contravariant string|Stringable
 - [BC] The parameter $message of Psr\Log\LoggerTrait#critical() changed from no type to a non-contravariant string|Stringable
 - [BC] The parameter $message of Psr\Log\LoggerTrait#error() changed from no type to a non-contravariant string|Stringable
 - [BC] The parameter $message of Psr\Log\LoggerTrait#warning() changed from no type to a non-contravariant string|Stringable
 - [BC] The parameter $message of Psr\Log\LoggerTrait#notice() changed from no type to a non-contravariant string|Stringable
 - [BC] The parameter $message of Psr\Log\LoggerTrait#info() changed from no type to a non-contravariant string|Stringable
 - [BC] The parameter $message of Psr\Log\LoggerTrait#debug() changed from no type to a non-contravariant string|Stringable
 - [BC] Symfony\Component\HttpKernel\Event\ControllerEvent was marked "@internal"

The Psr\Log-related BC breaks are because psr/log:^2.0 adds types. If consumers are still using psr/log:^1.0 this will be irrelevant.