[TRIVIAL] Typo Fix

## What changes were proposed in this pull request?
Fix a typo

## How was this patch tested?
no tests

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #14772 from zhengruifeng/minor_numClasses.

mllib/src/main/scala/org/apache/spark/ml/classification/Classifier.scala

@@ -83,7 +83,7 @@ abstract class Classifier[
       case Row(label: Double, features: Vector) =>
         require(label % 1 == 0 && label >= 0 && label < numClasses, s"Classifier was given" +
           s" dataset with invalid label $label.  Labels must be integers in range" +
-          s" [0, 1, ..., $numClasses), where numClasses=$numClasses.")
+          s" [0, $numClasses).")
         LabeledPoint(label, features)
     }
   }