tools: enable linter for `tools/icu/**`

PR-URL: https://github.com/nodejs/node/pull/56176
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>

eslint.config.mjs

@@ -50,7 +50,6 @@ export default [
       'test/addons/??_*',
       'test/fixtures/**',
       'tools/github_reporter/**',
-      'tools/icu/**',
     ],
   },
   // #endregion