[1.x] Flush monolog state between requests

[nunomaduro]

This pull request ensures the monolog state - handlers and processors - are reset between requests.

An example is on the usage of FingersCrossedHandler. Previously, when using the FingersCrossedHandler, the following requests printed two logs:

Route::get('/info', fn () => info('info'));
Route::get('/critical', fn () => logger()->critical('critical'));

// 2 requests...
GET /info
GET /critical

// laravel.log (Assuming an `'action_level' => 'critical'`)
line 1: info
line 2: critical

Now, because the FingersCrossedHandler is flushed between requests, the output is:

// 2 requests...
GET /info
GET /critical

// laravel.log (Assuming an `'action_level' => 'critical'`)
line 1: critical