remove scala collection compat

build.sbt

@@ -119,7 +119,6 @@ lazy val kernelLaws = crossProject(JSPlatform, JVMPlatform, NativePlatform)
   .settings(testingDependencies)
   .jsSettings(commonJsSettings)
   .jvmSettings(commonJvmSettings)
-  .jvmSettings(libraryDependencies += "org.scala-lang.modules" %% "scala-collection-compat" % "2.11.0" % Test)
   .nativeSettings(commonNativeSettings)
 
 lazy val algebraSettings = Seq[Setting[?]](

kernel-laws/jvm/src/test/scala/cats/kernel/laws/JvmLawTests.scala

@@ -22,12 +22,12 @@
 package cats.kernel
 package laws
 
+import cats.kernel.compat.scalaVersionSpecific.*
 import cats.kernel.instances.currency.*
 import cats.kernel.laws.discipline.*
 import munit.DisciplineSuite
 import java.util.Currency
 import org.scalacheck.{Arbitrary, Cogen, Gen}
-import scala.jdk.CollectionConverters.*
 
 class JvmLawTests extends TestsConfig with DisciplineSuite {
   implicit private val arbitraryCurrency: Arbitrary[Currency] = Arbitrary(

kernel/src/main/scala-2.12/cats/kernel/compat/scalaVersionSpecific.scala

@@ -21,7 +21,8 @@
 
 package cats.kernel.compat
 import scala.annotation.{Annotation, StaticAnnotation}
-import scala.collection.{IterableLike, TraversableLike}
+import scala.collection.{mutable, IterableLike, TraversableLike}
+import scala.collection.convert.ImplicitConversionsToScala.*
 
 private[cats] object scalaVersionSpecific {
 
@@ -48,4 +49,8 @@ private[cats] object scalaVersionSpecific {
       that: T
     )(implicit w1: A => TraversableLike[El1, Repr1], w2: T => IterableLike[El2, Repr2]) = (a, that).zipped
   }
+
+  implicit class setExtension[A](private val a: A) extends AnyVal {
+    def asScala(s: java.util.Set[A]): mutable.Set[A] = `set asScala`(s)
+  }
 }

kernel/src/main/scala-2.13+/cats/kernel/compat/scalaVersionSpecific.scala

@@ -24,6 +24,8 @@ package kernel
 
 package compat
 import scala.annotation.{Annotation, StaticAnnotation}
+import scala.collection.mutable
+import scala.jdk.CollectionConverters.*
 
 private[cats] object scalaVersionSpecific {
 
@@ -35,4 +37,8 @@ private[cats] object scalaVersionSpecific {
   implicit class iterableOnceExtension[A](private val io: IterableOnce[A]) extends AnyVal {
     def reduceOption(f: (A, A) => A): Option[A] = io.iterator.reduceOption(f)
   }
+
+  implicit class setExtension[A](private val s: java.util.Set[A]) extends AnyVal {
+    def asScala: mutable.Set[A] = SetHasAsScala(s).asScala
+  }
 }

kernel/src/main/scala/cats/kernel/instances/CurrencyInstances.scala

@@ -25,10 +25,5 @@ package instances
 import java.util.Currency
 
 trait CurrencyInstances {
-  implicit def catsKernelStdHashForCurrency: Hash[Currency] = new CurrencyHash
-}
-
-class CurrencyHash extends Hash[Currency] {
-  override def eqv(x: Currency, y: Currency): Boolean = x.getCurrencyCode().equals(y.getCurrencyCode())
-  override def hash(x: Currency): Int = x.getCurrencyCode().hashCode()
+  implicit val catsKernelStdHashForCurrency: Hash[Currency] = Hash.fromUniversalHashCode[Currency]
 }