non-'Sendable' type issues

```
Static property 'sharedInstance' is not concurrency-safe because non-'Sendable' type 'Keychain' may have shared mutable state
Let 'defaultAlgorithm' is not concurrency-safe because non-'Sendable' type 'Generator.Algorithm' may have shared mutable state
```

Happens on Xcode 16.4
Lib v 4.0.0
Thanks