Update Kotlin to 2.0.21 (sol4k#95)

Update kotlinx serialization (sol4k#90)

Kotlin 2.0 upgrade (sol4k#88)

Update version and documentation (sol4k#79)

Update Gradle and Kotlin (sol4k#67)

Kotlin 1.9.22 & other library updates (sol4k#60)

Update Kotlin version to 1.9.20 (sol4k#59)

Update Kotlin to 1.9 (sol4k#53)

Update Kotlin (sol4k#45)

APIs for signing messages and verifying signatures (sol4k#44)