Swift 6 & Strict Concurrency

What's Changed

• Updates the framework to use Swift 6 and turns on strict concurrency by @Cordavi in #16
• Updates the stride type from Int to TimeInterval for func advance(by stride:) to allow more control over the amount of time being advanced by @ashlirankin in #15

New Contributors

• @ashlirankin made their first contribution in #15

Full Changelog: 1.1.0...1.2.0