Require isort on all Python files. (#8420)

demo/guide-python/sklearn_parallel.py

@@ -2,11 +2,13 @@
 Demo for using xgboost with sklearn
 ===================================
 """
-from sklearn.model_selection import GridSearchCV
-from sklearn.datasets import fetch_california_housing
-import xgboost as xgb
 import multiprocessing
 
+from sklearn.datasets import fetch_california_housing
+from sklearn.model_selection import GridSearchCV
+
+import xgboost as xgb
+
 if __name__ == "__main__":
     print("Parallel Parameter optimization")
     X, y = fetch_california_housing(return_X_y=True)