Volume capacity values properties not generated for tvOS

### [Volume capacity values](https://developer.apple.com/documentation/foundation/urlresourcevalues#Volume-capacity-values)

```swift
var volumeAvailableCapacity: Int?
…
var volumeTotalCapacity: Int?
```
are available for tvOS9+
but you have whole `extension` wrapped with `#if os(iOS)`

![Image](https://github.com/user-attachments/assets/3ea1fdf7-7d03-4240-9da0-ca850b58a6bb)