Track TODO comments in types/codec.go

The file `types/codec.go` contains TODO comments that need to be addressed:
- Uncomment the lines related to `EthAccount` after moving into migrations for the EVM version.

Relevant TODO comments:
```go
// TODO: uncomment after moving into migrations for EVM version
// &EthAccount{},
```

File: [types/codec.go](https://github.com/evmos/os/blob/main/types/codec.go)
