Update load.environment for phpdotenv 4.x.

Author: agger-magenta

load.environment.php

@@ -11,7 +11,7 @@
 /**
  * Load any .env file. See /.env.example.
  */
-$dotenv = new Dotenv(__DIR__);
+$dotenv = Dotenv::createImmutable(__DIR__);
 try {
   $dotenv->load();
 }