[feature/oauth] Forgot to remove placeholder comment

PHPBB3-11673

phpBB/phpbb/auth/provider/oauth/service/bitly.php

@@ -66,7 +66,6 @@ class phpbb_auth_provider_oauth_service_bitly extends phpbb_auth_provider_oauth_
 	{
 		if (!($this->service_provider instanceof \OAuth\OAuth2\Service\Bitly))
 		{
-			// TODO: make exception class and use language constant
 			throw new phpbb_auth_provider_oauth_service_exception('AUTH_PROVIDER_OAUTH_ERROR_INVALID_SERVICE_TYPE');
 		}