Updated the files.

my-app/node_modules/piscina/test/fixtures/esm-async.mjs

@@ -0,0 +1,12 @@
+import util from 'util';
+const sleep = util.promisify(setTimeout);
+
+// eslint-disable-next-line no-eval
+function handler (code) { return eval(code); }
+
+async function load () {
+  await sleep(100);
+  return handler;
+}
+
+export default load();