Installation Error - Undefined class constant 'MYSQL_ATTR_INIT_COMMAND' #73

I tried to install php-censor on a VM wich runs Debian with postgresql (without MySQL - I didn't activate pdo_mysql, because I want to use Postgresql ...) and I had this error :

PHP Fatal error: Undefined class constant 'MYSQL_ATTR_INIT_COMMAND' in /vagrant/php-censor.local/src/PHPCensor/Command/InstallCommand.php on line 429
PHP Stack trace:
PHP 1. {main}() /vagrant/php-censor.local/bin/console:0
PHP 2. Symfony\Component\Console\Application->run() /vagrant/php-censor.local/bin/console:11
PHP 3. Symfony\Component\Console\Application->doRun() /vagrant/php-censor.local/vendor/symfony/console/Application.php:123
PHP 4. Symfony\Component\Console\Application->doRunCommand() /vagrant/php-censor.local/vendor/symfony/console/Application.php:192
PHP 5. Symfony\Component\Console\Command\Command->run() /vagrant/php-censor.local/vendor/symfony/console/Application.php:846
PHP 6. PHPCensor\Command\InstallCommand->execute() /vagrant/php-censor.local/vendor/symfony/console/Command/Command.php:264
PHP 7. PHPCensor\Command\InstallCommand->verifyDatabaseDetails() /vagrant/php-censor.local/src/PHPCensor/Command/InstallCommand.php:86