test: remove keyed queue timer flush

src/plugin-sdk/keyed-async-queue.test.ts

@@ -100,7 +100,7 @@ describe("enqueueKeyedTask", () => {
         }),
       ).rejects.toThrow("boom");
 
-      await new Promise((resolve) => setTimeout(resolve, 0));
+      await new Promise<void>((resolve) => setImmediate(resolve));
       expect(unhandled).toStrictEqual([]);
     } finally {
       process.off("unhandledRejection", onUnhandledRejection);