update setup.py

csst_ifs_sim/csst_ifs_sim.py

@@ -5061,7 +5061,7 @@ if __name__ == "__main__":
     applyhole = 'no'
 
     if CSST_unittest:
-        dir_path = os.path.join(os.environ['UNIT_TEST_DATA_ROOT'], 'ifs_sim')
+        dir_path = os.path.join(os.environ['UNIT_TEST_DATA_ROOT'], 'ifs_sim/')
     else:
         dir_path = '../'