feat: Added logging when localized key is not found

fix: Bundle not included as cache key in strings localization

Also converted to use Mutext

Updated README

fix: Concurrency issue accessing environment values during rendering

feat: Require Swift 6.0

fix: Missing Sendable conformance for RenderResult

chore: Converted to use swift testing

… instead of XCTest

fix: Removed usage of NSLock.withLock

feat: Enabled strict concurrency checking

Also fixed all issues

feat: Added support for localized keys and formatting in Text