Version 4.5.1

A small set of security fixes & upgrades today (v4.5.1)
- Large refactor of the payment system under the hood -- you shouldn’t notice anything different, but future development will be faster and easier.
- A few small bugs were fixed during this process, including handling edgecases with multiple upgrades and downgrades in succession and automatically refunding duplicate subscriptions.
- Several small security fixes, including upgraded deprecated dependencies.
- Some of these will have caused you to log out! Sorry about that!
- Improved truncation handling for long context chats and adventures.
- Fixed a bug which allowed very long chats to error out under some circumstances.