better handling of organization cancellation
better handling of organization cancellation

An organization subscription will be automatically cancelled by Stripe if 4 payments on the account fail.
Previously, we assumed a subscription would always be present.
This update handles the InvalidRequestError arising when the subscription has already been cancelled.

- fixes #1053

MuckRock/muckrock,MuckRock/muckrock,MuckRock/muckrock,MuckRock/muckrock