fix caused by the upgrade of dirac from python2->python3

[zhangxiaomei]

DIRAC environment is not set!
[2022-09-28 11:25:43.301 +0200 CEST][JSUB|ERROR]: Submit job to DIRAC failed: submission script exited with return code 1
[2022-09-28 11:25:43.302 +0200 CEST][JSUB|ERROR]: DIRAC environment not properly setup?
[2022-09-28 11:25:43.302 +0200 CEST][JSUB|ERROR]: stdout of submission script: