## Description

Update `next_epoch_stake` when redeeming a fungible staked sui. This
value is used as a sanity check that everything matches up at the end of
an epoch.

## Test plan

```
sui$ cargo nextest run -p sui-framework-tests
```

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [x] Protocol: Protocol bumped to 66, introducing a framework change to
fix `next_epoch_stake` book-keeping while redeeming fungible staked sui.
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:
- [ ] REST API:

---------

Co-authored-by: Arun Koshy <arun@mystenlabs.com>
Co-authored-by: Sam Blackshear <sam@mystenlabs.com>
Co-authored-by: Emma Zhong <emmazhongjy@gmail.com>