Add php84-pdo package

[mr-flibble]

Hello, it's possible to add pdo PHP module?

Some backup plugins like WPvivid Backup Plugin are recommending php84-pdo for it for better backup performance,

The PDO extension is not detected. Please install the extension first.

It is recommended to choose PDO option if pdo_mysql extension is installed on your server, which lets you backup and restore your site faster.