Swift 6 - Concurrency

[james-ff]

Hello,

I've noticed that part of this library may require updating for the upcoming concurrency changes in Swift 6

After turning on strict concurrency checks I'm seeing the following error in my project for static properties of the LogLevel class:

Static property 'debug' is not concurrency-safe because it is not either conforming to 'Sendable' or isolated to a global actor; this is an error in Swift 6

Relevant guide:

• https://www.avanderlee.com/swift/sendable-protocol-closures/#preparing-your-code-for-swift-6-with-strict-concurrency-checking