Convert config to ESM

src/_data/i18n.js

@@ -1,7 +1,10 @@
-const fs = require("fs");
-const path = require("path");
+import fs from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
 
-module.exports = function () {
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+export default function () {
   const localesDir = path.join(__dirname, "..", "locales");
   const dict = {};
   for (const file of fs.readdirSync(localesDir)) {
@@ -10,4 +13,4 @@ module.exports = function () {
     dict[locale] = JSON.parse(fs.readFileSync(path.join(localesDir, file), "utf8"));
   }
   return dict;
-};
+}