fix: use dotenv in mongodb.ts file

src/lib/mongo/mongodb.ts

@@ -1,7 +1,9 @@
 // This approach is taken from https://github.com/vercel/next.js/tree/canary/examples/with-mongodb
 import { MongoClient } from 'mongodb';
-import { MONGODB_URI } from '$env/static/private';
+import dotenv from 'dotenv';
+dotenv.config();
 
+const MONGODB_URI = process.env.MONGODB_URI;
 if (!MONGODB_URI) {
 	throw new Error('Invalid/Missing environment variable: "MONGODB_URI"');
 }