test: use platform in directory name

To rule out the runner matrix causing problems

slug.js

@@ -0,0 +1,6 @@
+import uniqueSlug from "unique-slug";
+function slug() {
+	return uniqueSlug();
+}
+
+console.log(slug());

test/main.js

@@ -1,13 +1,18 @@
 /* eslint-disable no-empty */
 
 import { Writable, pipeline } from "node:stream";
+import os from "node:os";
 import { stream } from "@eik/common";
-import slug from "unique-slug";
+import uniqueSlug from "unique-slug";
 import tap from "tap";
 import fs from "node:fs";
 
 import Sink from "../lib/main.js";
 
+function slug() {
+	return `${os.platform()}/${uniqueSlug()}`;
+}
+
 // Ignore the value for "timestamp" field in the snapshots
 tap.cleanSnapshot = (s) => {
 	const regex = /"timestamp": [0-9.]+,/gi;