fix endpoint for task method

Author: iLLiCiTiT

ayon_api/server_api.py

@@ -7899,7 +7899,7 @@ def get_task_thumbnail(
                 valid.
 
         """
-        return self.get_thumbnail(project_name, "folder", task_id)
+        return self.get_thumbnail(project_name, "task", task_id)
 
     def get_version_thumbnail(
         self,