# Description
Switch `to_folded_case` to a proper case fold instead of
`str::to_lowercase` now that unicase exposes its `to_folded_case`
method.

Rel: nushell#10884, seanmonstar/unicase#61

# User-Facing Changes

Case insensitive sorts now do proper case folding.

Old behavior:

```nushell
[dreißig DREISSIG] | sort -i
# => ╭───┬──────────╮
# => │ 0 │ DREISSIG │
# => │ 1 │ dreißig  │
# => ╰───┴──────────╯
```

New behavior:

```nushell
[dreißig DREISSIG] | sort -i
# => ╭───┬──────────╮
# => │ 0 │ dreißig  │
# => │ 1 │ DREISSIG │
# => ╰───┴──────────╯
```