IOS Build Error

I tried to build the package for IOS but i get a single dumb error.

The function used in
Merge.swift:174

```swift
guard tile != nil else { throw CLIError("Failed to load the resource at '\(outputUrl.path())'") }
```
"outputUrl.path()"
-> "'path(percentEncoded:)' is only available in iOS 16.0 or newer"

The fix should be quite simple I think.
@trasch 