Update std/shared/src/main/scala/cats/effect/std/NonEmptyHotswap.scala

Co-authored-by: Arman Bilge <armanbilge@gmail.com>

Author: morgen-peschke

std/shared/src/main/scala/cats/effect/std/NonEmptyHotswap.scala

@@ -68,7 +68,7 @@ sealed trait NonEmptyHotswap[F[_], R] {
    * If [[swap]] is called after the lifetime of the [[NonEmptyHotswap]] is over, it will raise
    * an error, but will ensure that all resources are finalized before returning.
    */
-  def swap(next: Resource[F, R]): F[R]
+  def swap(next: Resource[F, R]): F[Unit]
 
   /**
    * Gets the current resource. The returned resource is guaranteed to be available for the