fix ktlint

Author: AndreiKingsley

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/countDistinct.kt

@@ -46,7 +46,6 @@ public fun AnyFrame.countDistinct(): Int = countDistinct { all() }
  */
 internal interface CountDistinctDocs
 
-
 /**
  * {@include [CountDistinctDocs]}
  * {@include [SelectingColumns.Dsl]}