wasi-threads: fix import name

As @TerrorJack pointed out in bytecodealliance#5484, that PR implements an older
name--`thread_spawn`. This change uses the now-official name from the
specification--`thread-spawn`.

Author: abrown

crates/wasi-threads/src/lib.rs

@@ -112,7 +112,7 @@ pub fn add_to_linker<T: Clone + Send + 'static>(
 ) -> anyhow::Result<SharedMemory> {
     linker.func_wrap(
         "wasi",
-        "thread_spawn",
+        "thread-spawn",
         move |mut caller: Caller<'_, T>, start_arg: i32| -> i32 {
             log::trace!("new thread requested via `wasi::thread_spawn` call");
             let host = caller.data().clone();