Add check if notebook is still waiting for worker

[Piotr]

Please check if session is still waiting for worker before spinning new worker. I think fix code should be here

mercury/mercury/apps/ws/tasks.py

Lines 62 to 69 in fc0d4b2

 notebook_id = job_params["notebook_id"] 
 session_id = job_params["session_id"] 
 worker_id = job_params["worker_id"] 
 worker_url = f"http://{worker_ip}/start/{notebook_id}/{session_id}/{worker_id}" 
 log.info(f"Try to start worker {worker_url}") 
 response = requests.get(worker_url, timeout=5) 
 log.info(f"Response from worker {response.status_code}") 
 if response.status_code == 200: