[Fix] no_shared_fs should be under the field runner (#300)

“no_shared_fs" should be under the field "runner"

Change
no_shared_fs = config.experiment.get("no_shared_fs", False) 
to 
no_shared_fs = runner_config.get("no_shared_fs", False)

flagscale/runner/runner_train.py

@@ -122,7 +122,7 @@ def _get_runner_cmd_train(
     rdzv_id = runner_config.get("rdzv_id", "default")
     log_dir = runner_config.get("log_dir", logging_config.details_dir)
     log_dir = os.path.abspath(log_dir)
-    no_shared_fs = config.experiment.get("no_shared_fs", False)
+    no_shared_fs = runner_config.get("no_shared_fs", False)
     if no_shared_fs:
         log_dir = os.path.join(log_dir, f"host")
     else: