Fix minor issues

package.json

@@ -9,6 +9,7 @@
   },
   "author": "Bartłomiej Pluta <noreply.git@mx.bartlomiejpluta.com>",
   "license": "ISC",
+  "type": "module",
   "bin": {
     "actual-importer": "./dist/index.js"
   },

src/server/index.ts

@@ -1,4 +1,4 @@
-const { mkdir } = require('node:fs/promises');
+import { mkdir } from 'node:fs/promises';
 import * as api from "@actual-app/api";
 import { ServerConfig } from "@/types/config";
 import { Transaction } from "@/types/transaction";