Infant in seat not properly counted (Delta)

[esqew]

When generating a Delta purchase link from a Matrix itinerary which includes an infant in seat, the extension does not properly calculate the value for the resulting paxCount URL parameter to include said infant in seat. When manually adjusting paxCount from 1 to 2, the resulting purchase page works as expected.

Not personally sure if this is Delta-specific or a symptom of a broader bug.

I'd be more than happy to take a stab at submitting a PR for this when said infant in seat gives me a breather.