[Enhancement]Replace getPdo with getReadPdo

[maoxuner]

laravel-scout-tntsearch-driver/src/Console/ImportCommand.php

Line 44 in e48c84d

$tnt->setDatabaseHandle($db->getPdo());

When importing, read only access is enough. I think it will be better to replace getPdo with getReadPdo if there is a read-and-write connection.

In my condition, I run tntsearch:import from a standalone instance with only read only access to my db. But getPdo always returns default pdo (from database write server config)