allow username in getUser

src/APnutI.php

@@ -662,7 +662,8 @@ class APnutI
         return $this->current_user;
     }
 
-    public function getUser(int $user_id, array $args = [])
+    // User ID or user name
+    public function getUser(int|string $user_id, array $args = [])
     {
         return new User($this->get('/users/' . $user_id, $args), $this);
     }