feat: relax type constraints for statistics functions

 The type constraints for the statistics functions `maxFor`, `medianFor`, and `percentileFor` in a dataframe were relaxed from `C : Comparable<C>` to `C : Comparable<*>?`, allowing for more flexible type usage. Changes were successfully implemented across relevant function declarations and also included necessary test validations. There were no errors reported during the implementation process.

Author: jetbrains-junie[bot]

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

@@ -81,7 +81,7 @@ public fun <T> DataFrame<T>.max(skipNaN: Boolean = skipNaNDefault): DataRow<T> =
 
 @Refine
 @Interpretable("Max1")
-public fun <T, C : Comparable<C & Any>?> DataFrame<T>.maxFor(
+public fun <T, C : Comparable<*>?> DataFrame<T>.maxFor(
     skipNaN: Boolean = skipNaNDefault,
     columns: ColumnsForAggregateSelector<T, C>,
 ): DataRow<T> = Aggregators.max<C>(skipNaN).aggregateFor(this, columns)
@@ -91,14 +91,14 @@ public fun <T> DataFrame<T>.maxFor(vararg columns: String, skipNaN: Boolean = sk
 
 @Deprecated(DEPRECATED_ACCESS_API)
 @AccessApiOverload
-public fun <T, C : Comparable<C & Any>?> DataFrame<T>.maxFor(
+public fun <T, C : Comparable<*>?> DataFrame<T>.maxFor(
     vararg columns: ColumnReference<C>,
     skipNaN: Boolean = skipNaNDefault,
 ): DataRow<T> = maxFor(skipNaN) { columns.toColumnSet() }
 
 @Deprecated(DEPRECATED_ACCESS_API)
 @AccessApiOverload
-public fun <T, C : Comparable<C & Any>?> DataFrame<T>.maxFor(
+public fun <T, C : Comparable<*>?> DataFrame<T>.maxFor(
     vararg columns: KProperty<C>,
     skipNaN: Boolean = skipNaNDefault,
 ): DataRow<T> = maxFor(skipNaN) { columns.toColumnSet() }
@@ -212,7 +212,7 @@ public fun <T> Grouped<T>.max(skipNaN: Boolean = skipNaNDefault): DataFrame<T> =
 
 @Refine
 @Interpretable("GroupByMax0")
-public fun <T, C : Comparable<C & Any>?> Grouped<T>.maxFor(
+public fun <T, C : Comparable<*>?> Grouped<T>.maxFor(
     skipNaN: Boolean = skipNaNDefault,
     columns: ColumnsForAggregateSelector<T, C>,
 ): DataFrame<T> = Aggregators.max<C>(skipNaN).aggregateFor(this, columns)
@@ -222,14 +222,14 @@ public fun <T> Grouped<T>.maxFor(vararg columns: String, skipNaN: Boolean = skip
 
 @Deprecated(DEPRECATED_ACCESS_API)
 @AccessApiOverload
-public fun <T, C : Comparable<C & Any>?> Grouped<T>.maxFor(
+public fun <T, C : Comparable<*>?> Grouped<T>.maxFor(
     vararg columns: ColumnReference<C>,
     skipNaN: Boolean = skipNaNDefault,
 ): DataFrame<T> = maxFor(skipNaN) { columns.toColumnSet() }
 
 @Deprecated(DEPRECATED_ACCESS_API)
 @AccessApiOverload
-public fun <T, C : Comparable<C & Any>?> Grouped<T>.maxFor(
+public fun <T, C : Comparable<*>?> Grouped<T>.maxFor(
     vararg columns: KProperty<C>,
     skipNaN: Boolean = skipNaNDefault,
 ): DataFrame<T> = maxFor(skipNaN) { columns.toColumnSet() }
@@ -302,7 +302,7 @@ public inline fun <T, G, reified C : Comparable<C & Any>?> GroupBy<T, G>.maxBy(
 public fun <T> Pivot<T>.max(separate: Boolean = false, skipNaN: Boolean = skipNaNDefault): DataRow<T> =
     delegate { max(separate, skipNaN) }
 
-public fun <T, R : Comparable<R & Any>?> Pivot<T>.maxFor(
+public fun <T, R : Comparable<*>?> Pivot<T>.maxFor(
     separate: Boolean = false,
     skipNaN: Boolean = skipNaNDefault,
     columns: ColumnsForAggregateSelector<T, R>,
@@ -388,7 +388,7 @@ public inline fun <T, reified C : Comparable<C & Any>?> Pivot<T>.maxBy(
 public fun <T> PivotGroupBy<T>.max(separate: Boolean = false, skipNaN: Boolean = skipNaNDefault): DataFrame<T> =
     maxFor(separate, skipNaN, intraComparableColumns())
 
-public fun <T, R : Comparable<R & Any>?> PivotGroupBy<T>.maxFor(
+public fun <T, R : Comparable<*>?> PivotGroupBy<T>.maxFor(
     separate: Boolean = false,
     skipNaN: Boolean = skipNaNDefault,
     columns: ColumnsForAggregateSelector<T, R>,

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/aggregation/aggregators/Aggregators.kt

@@ -124,7 +124,7 @@ public object Aggregators {
 
     // T: Comparable<T> -> T?
     // T : Comparable<T & Any>? -> T?
-    public fun <T : Comparable<T & Any>?> max(skipNaN: Boolean): Aggregator<T & Any, T?> = max.invoke(skipNaN).cast2()
+    public fun <T : Comparable<*>?> max(skipNaN: Boolean): Aggregator<T & Any, T?> = max.invoke(skipNaN).cast2()
 
     public val max: AggregatorOptionSwitch1<Boolean, Comparable<Any>, Comparable<Any>?>
         by withOneOption { skipNaN: Boolean ->
@@ -159,22 +159,22 @@ public object Aggregators {
         percentile: Double,
         skipNaN: Boolean,
     ): Aggregator<T & Any, T?>
-        where T : Comparable<T & Any>? =
+        where T : Comparable<*>? =
         this.percentile.invoke(percentile, skipNaN).cast2()
 
     // T: Comparable<T & Any>? -> T?
     public fun <T> percentileComparables(
         percentile: Double,
     ): Aggregator<T & Any, T?>
-        where T : Comparable<T & Any>? =
+        where T : Comparable<*>? =
         percentileCommon<T>(percentile, skipNaNDefault).cast2()
 
     // T: primitive Number? -> Double?
     public fun <T> percentileNumbers(
         percentile: Double,
         skipNaN: Boolean,
     ): Aggregator<T & Any, Double?>
-        where T : Comparable<T & Any>?, T : Number? =
+        where T : Comparable<*>?, T : Number? =
         percentileCommon<T>(percentile, skipNaN).cast2()
 
     @Suppress("UNCHECKED_CAST")
@@ -193,19 +193,19 @@ public object Aggregators {
     // T: primitive Number? -> Double?
     // T: Comparable<T & Any>? -> T?
     public fun <T> medianCommon(skipNaN: Boolean): Aggregator<T & Any, T?>
-        where T : Comparable<T & Any>? =
+        where T : Comparable<*>? =
         median.invoke(skipNaN).cast2()
 
     // T: Comparable<T & Any>? -> T?
     public fun <T> medianComparables(): Aggregator<T & Any, T?>
-        where T : Comparable<T & Any>? =
+        where T : Comparable<*>? =
         medianCommon<T>(skipNaNDefault).cast2()
 
     // T: primitive Number? -> Double?
     public fun <T> medianNumbers(
         skipNaN: Boolean,
     ): Aggregator<T & Any, Double?>
-        where T : Comparable<T & Any>?, T : Number? =
+        where T : Comparable<*>?, T : Number? =
         medianCommon<T>(skipNaN).cast2()
 
     @Suppress("UNCHECKED_CAST")