AtomicFU Gradle Plugin should not depend on kotlin-metadata-jvm

[fzhinkin]

AtomicFU Gradle Plugin transitively (though atomicfu-transformer) depends on kotlin-metadata-jvm.

Usage of a specific metadata version limits the range of Kotlin versions the plugin supports, and it also affects the Kotlin version required to compile the plugin.

Instead of using an explicitly dependency on a fixed kotlin-metadata-jvm version, the plugin should pick a version corresponding to a Kotlin compiler version used in a project applying the AFU GP.