[MINOR][ML] Rename TreeEnsembleModels to TreeEnsembleModel for PySpark

## What changes were proposed in this pull request?
Fix the typo of ```TreeEnsembleModels``` for PySpark, it should ```TreeEnsembleModel``` which will be consistent with Scala. What's more, it represents a tree ensemble model, so  ```TreeEnsembleModel``` should be more reasonable. This should not be used public, so it will not involve  breaking change.

## How was this patch tested?
No new tests, should pass existing ones.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #14454 from yanboliang/TreeEnsembleModel.

1 files changed, 3 insertions, 3 deletions

diff --git a/python/pyspark/ml/regression.py b/python/pyspark/ml/regression.py
index d88dc75353..1ae2bd4e40 100644
--- a/python/pyspark/ml/regression.py
+++ b/python/pyspark/ml/regression.py
@@ -749,7 +749,7 @@ class DecisionTreeModel(JavaModel):
 
 
 @inherit_doc
-class TreeEnsembleModels(JavaModel):
+class TreeEnsembleModel(JavaModel):
     """
     (private abstraction)
 
@@ -909,7 +909,7 @@ class RandomForestRegressor(JavaEstimator, HasFeaturesCol, HasLabelCol, HasPredi
         return RandomForestRegressionModel(java_model)
 
 
-class RandomForestRegressionModel(TreeEnsembleModels, JavaMLWritable, JavaMLReadable):
+class RandomForestRegressionModel(TreeEnsembleModel, JavaMLWritable, JavaMLReadable):
     """
     Model fitted by :class:`RandomForestRegressor`.
 
@@ -1047,7 +1047,7 @@ class GBTRegressor(JavaEstimator, HasFeaturesCol, HasLabelCol, HasPredictionCol,
         return self.getOrDefault(self.lossType)
 
 
-class GBTRegressionModel(TreeEnsembleModels, JavaMLWritable, JavaMLReadable):
+class GBTRegressionModel(TreeEnsembleModel, JavaMLWritable, JavaMLReadable):
     """
     Model fitted by :class:`GBTRegressor`.