Fix module warnings while creating VThreads with attachment #53
Description
#50 has introduced this warning:
[INFO] Running io.netty.loom.VirtualMultithreadIoEventLoopGroupTest
WARNING: A restricted method in java.lang.Thread$Builder$OfVirtual has been called
WARNING: java.lang.Thread$Builder$OfVirtual::unstarted has been called by io.netty.loom.EventLoopScheduler in an unnamed module (file:/home/forked_franz/IdeaProjects/Netty-VirtualThread-Scheduler/core/target/classes/)
WARNING: Use --enable-native-access=ALL-UNNAMED to avoid a warning for callers in this module
WARNING: Restricted methods will be blocked in a future release unless native access is enabled