Simplify department name retrieval logic in Redis class

Replaced JSON decoding with direct object casting for department data, reducing unnecessary parsing overhead. This change ensures a more efficient and straightforward handling of the `get_department_name` function.

services/nginx/app/classes/redis.php

@@ -105,12 +105,12 @@ class redis implements redis_i
     public function get_department_name(int $department_id): string|null
     {
         // Get the department name
-        $tmp_department = $this->get('department_' . $department_id);
+        $tmp_department = (object)$this->get('department_' . $department_id) ?? null;
         if ($tmp_department === 'IS_EMPTY_OR_NULL' || $tmp_department === null) {
             return null;
         }
         // Return the department name
-        return json_decode($tmp_department, true)->name;
+        return $tmp_department->name;
     }
 
     /**