update setup.py

tests/test_ifs_sim.py

@@ -37,7 +37,7 @@ class TestDemoFunction(unittest.TestCase):
         
         d=1
         
-        subprocess.run(['csst_ifs_sim', dir_path])
+        subprocess.run(['csst_ifs_sim.py', dir_path])
         
         #csst_ifs_sim dir_path