index out of bounds: the len is 1 but the index is 2 when trying to decode

```
[brain@ignatenko-w541 ~]$ echo "👟👜👣👣👦🐁" | base100 -d
thread 'main' panicked at 'index out of bounds: the len is 1 but the index is 2', src/main.rs:91:20
note: Run with `RUST_BACKTRACE=1` for a backtrace.
Aborted (core dumped)
```