Cancelation Event Cancels Membership Instead of Subscription

[misfist]

Describe the bug
The cancellation event cancels the member's membership rather than just the subscription.

What should happen is that the subscription is canceled so they're no longer billed, but the membership should remain active until the next bill date.

https://github.com/strangerstudios/pmpro-ccbill/blob/dev/webhook.php#L348-L367

To Reproduce
Steps to reproduce the behavior:

Event sent to:
https://{{base_url}}/wp-admin/admin-ajax.php?action=ccbill-webhook&eventType=Cancellation&clientAccnum={{clientAccnum}}&clientSubacc={{clientSubacc}}&eventGroup={{eventGroup}}&validate=true&creationDate=2024-07-14T05:24:49.122Z

Event data sent:

subscriptionId {{subscriptionId}}
transactionId 14621b22-b4a1-4d50-80f7-a4e69eadf8a3
timestamp 2024-07-14T05:20:50.703Z
reason Invalid Input.
source FORM

Screenshots
If applicable, please attach a screenshot to make your issue clearer.

Expected behavior
A clear and concise description of what you expected to happen.

[andrewlimaza]

This issue is related to #42