## Description 

Changes voting procedure for determining next protocol version, so that
validators can select the highest supported version instead of the next
consecutive version.

## Test Plan 

cargo simtest

### Type of Change (Check all that apply)

- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [x] breaking change for FNs (FN binary must upgrade)
- [x] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes

Fullnode operators will need to upgrade to a binary that supports
protocol version 7.