[core] Remove redundant AtomicFU runtime dependency from mirai-core-utils

mirai-core-utils/build.gradle.kts

@@ -35,7 +35,6 @@ kotlin {
                 api(`kotlinx-serialization-json`)
                 api(`kotlinx-coroutines-core`)
 
-                implementation(`kotlinx-atomicfu`)
                 implementation(`kotlinx-serialization-protobuf`)
                 relocateImplementation(`ktor-io_relocated`)
             }