Work around for change in js_of_ocaml 5.9.0

`js_of_ocaml` 5.9.0 started using `node:` prefixed modules, which do not exist
on old node versions.

test/dune

@@ -222,7 +222,7 @@
    (<> %{os_type} Win32)
    (<> %{architecture} i386)
    (<> %{architecture} riscv)))
- (libraries picos))
+ (libraries picos js_of_ocaml))
 
 ;;
 

test/test_js_of_ocaml.ml

@@ -1,6 +1,6 @@
 open Picos
 
 let () =
-  Printf.printf "Hello, from js_of_ocaml with Picos!\n%!";
   let trigger = Trigger.create () in
-  Trigger.signal trigger
+  Trigger.signal trigger;
+  match Trigger.await trigger with None -> () | Some _ -> assert false