[ci][python] apply isort to python-package/lightgbm/sklearn.py #3958 (#3973)
[ci][python] apply isort to python-package/lightgbm/sklearn.py #3958 (#3973)


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