Updates & Enable MinGW

[aSemy]

Updates, tidyings, and support MinGW (Fix #5)

Summary

• version bumps
  • Gradle 8.1.1
  • Update Kotlin to 1.8.22
  • AssertK 0.26.1 (which now supports MinGW)
  • Kotlinx Serialization 1.5.1
  • Kotlinx Benchmark 0.4.8
  • Dokka 1.8.20
• Enable the mingw() target, since AssertK now supports it
• Move plugin versions to buildSrc/build.gradle.kts. Helps keep the build scripts consistent and cleaner, so all plugin versions are defined in one place
• disable Configuration Cache. Kotlin Multiplatform will hopefully support it in 1.9.
• GitHub Workflow updates
  • added PR trigger, so pull requests will be automatically tested
  • re-enable Windows, since it now works, hopefully!
  • cache Kotlin Konan, to improve the build times.
  • Add concurrency cancellation. The builds will now take much longer, because running all tests on all machines is slow (even with caching). Cancelling them when a new build comes it will stop the build queue getting clogged if lots of commits are pushed in quick succession.
  • Removed the --no-cc flag since it's disabled at the project level in gradle.properties

See aSemy#1, which successfully built on all platforms 🎉

[alllex]

This looks good, thanks!