Add Parallel Support for Pint

[onairmarc]

Now that Pint has experimental support for the --parallel flag, it would be beneficial to enable this option in Duster as well.

Since the flag is still experimental, I understand that we might want to wait until it's stable; however, it's worth bringing up the conversation.

[mattstauffer]

Thanks so much for this! We're talking about it and we'll try to respond ASAP with a reasoned-out plan.