Fix latest pytorch '_get_socket_with_port' import error (#5654)

The latest PyTorch deleted the '_get_socket_with_port' API, replacing it
with 'get_free_port'.

Fixes: #5603

deepspeed/elasticity/elastic_agent.py

@@ -6,7 +6,7 @@
 from torch.distributed.elastic.agent.server.local_elastic_agent import LocalElasticAgent
 from typing import Any, Dict, Optional, Tuple
 from datetime import datetime
-from torch.distributed.elastic.agent.server.api import _get_socket_with_port
+from torch.distributed.elastic.utils.distributed import get_free_port
 from torch.distributed.elastic.metrics import put_metric
 from torch.distributed.elastic.agent.server.api import (
     RunResult,
@@ -48,7 +48,7 @@ def _set_master_addr_port(store: Store,
                               master_port: Optional[int],
                               local_addr: Optional[str] = None):
         if master_port is None:
-            sock = _get_socket_with_port()
+            sock = get_free_port()
             with closing(sock):
                 master_port = sock.getsockname()[1]