X is only available in iOS 14.0 or newer

I get a lot of errors when I try to build for iOS. My project targets iOS 15 so I don't think this should be an issue.

```
Swift Compiler Error (Xcode): 'Logger' is only available in iOS 14.0 or newer
/Users/runner/.pub-cache/hosted/pub.dev/workmanager_apple-0.9.1+1/ios/Sources/workmanager_apple/LoggingDebugHandler.swift:7:28
```