Use stderr by default (#31)

Author: firecow

src/FilebeatLogging/FilebeatLoggingServiceProvider.php

@@ -23,7 +23,7 @@ public function register(): void
             'driver'               => 'custom',
             'channel'              => 'filebeat',
             'extras'               => json_decode(env('FILEBEAT_LOGGER_EXTRAS', '{}'), associative: true, flags: JSON_THROW_ON_ERROR),
-            'stream'               => env('FILEBEAT_LOGGER_STREAM', 'php://stdout'),
+            'stream'               => env('FILEBEAT_LOGGER_STREAM', 'php://stderr'),
             'rotating'             => env('FILEBEAT_LOGGER_ROTATING', false),
             'httpContextProcessor' => RequestProcessor::class,
             'via'                  => FilebeatLoggerFactory::class,