chore(lint): burn down remaining warnings to zero

src/preferences.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect, beforeEach, afterEach } from 'vitest';
-import { mkdtempSync, rmSync, readFileSync, writeFileSync, mkdirSync } from 'fs';
+import { mkdtempSync, rmSync, readFileSync, writeFileSync } from 'fs';
 import { resolve } from 'path';
 import { tmpdir } from 'os';
 import { loadPreferences, savePreference } from './preferences.js';