update inspect_dag_group_run.py

csst_dag/cli/inspect_dag_group_run.py

-import sys
 import os
+import sys
+import joblib
 
+# get dag_group_run hash
 dag_group_run_hash = sys.argv[1]
-
 assert len(dag_group_run_hash) == 40
-import joblib
 
+# get file path
 file_path = os.path.join(
     os.getenv("HOME"),
     "csst_dag",
     f"{dag_group_run_hash}.joblib",
 )
 
+# load DAG group run
 data = joblib.load(file_path)
 dag_group_run = data["dag_group_run"]
 dag_run_list = data["dag_run_list"]