test(generators): run release-please-utils tests under vitest

The file was doubly dead: the vitest include lacked lib/*.test.mjs and
the file imported node:test, so no runner ever executed it. The include
now picks up lib .mjs tests and the imports move to vitest (node:assert
keeps the original assertion style) — all 5 assertions live. (S5)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

turbo/generators/lib/release-please-utils.test.mjs

@@ -1,4 +1,6 @@
-import { test, describe } from "node:test";
+// Runs under vitest (the generators vitest include picks up lib/*.test.mjs);
+// node:assert keeps the original assertion style.
+import { test, describe } from "vitest";
 import assert from "node:assert/strict";
 import fs from "node:fs";
 import path from "node:path";

turbo/generators/vitest.config.ts

@@ -4,7 +4,7 @@ export default defineConfig({
   test: {
     globals: true,
     environment: "node",
-    include: ["*.test.ts", "lib/*.test.ts", "__tests__/*.test.ts"],
+    include: ["*.test.ts", "lib/*.test.{ts,mjs}", "__tests__/*.test.ts"],
     clearMocks: true,
     restoreMocks: true,
     // The core-package `*.e2e.test.ts` files each do a full `pnpm install`