cancellation_effective_date missing in subscription model

[DonvdH]

Paddle provides a cancellation_effective_date field which is currently missing in the subscription model:
https://developer.paddle.com/webhook-reference/3c0355dc446b0-subscription-cancelled
"The date the cancellation should come into effect, taking the customer’s most recent payment into account. The customer should be able to use the service they've subscribed to up until this date."

This is an important field because it is otherwise unknown how long the service should still be provided after cancellation.

Required line to be added in models.py under 'class Subscription(PaddleBaseModel):':
cancellation_effective_date = models.DateTimeField(null=True, blank=True)