`titleCase` insert extra space when convert a valid titleCase string

### Environment

Any

### Reproduction

```ts
import { titleCase } from 'scule'

console.log(titleCase('Hello World')) // -> `Hello  World`

console.log(titleCase(titleCase('Hello World'))) // -> `Hello   World`
```

### Describe the bug

It should be left as it is.

### Additional context

_No response_

### Logs

_No response_