[ci][python] apply isort to docs/conf.py (#3958) (#3959)
[ci][python] apply isort to docs/conf.py (#3958) (#3959)


microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,microsoft/LightGBM,microsoft/LightGBM,henry0312/LightGBM,microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM