Add status code to failed API send verbose log.

[danielmorell]

When an occurrence send fails with an error status code, we should include the status code in the verbose log message.

rollbar-php/src/RollbarLogger.php

Lines 271 to 273 in d9a40c8

	$this->verboseLogger()->error(
	'Occurrence rejected by the API: ' . ($info['message'] ?? 'message not set')
	);

This should also be backported to v3.