Enabled placeholders for "in" method in ExpressionBuilder

I would use:
```php
use Doctrine\DBAL\Connection;
use Doctrine\DBAL\Query\QueryBuilder;

$qb = new QueryBuilder(...);
$qb
    ->select('a')
    ->from('articles', 'a')
    ->where($qb->expr()->in(
        'a.comments',
        $qb->createPositionalParameter([1, 2, 3], Connection::PARAM_INT_ARRAY
    ))
;
```