Update scala-library to 2.13.15

Author: scala-steward-bot

build.sbt

@@ -169,7 +169,7 @@ lazy val commonSettings = Def.settings(
   scalapropsCoreSettings,
   (Compile / unmanagedResources) += (LocalRootProject / baseDirectory).value / "LICENSE.txt",
   scalaVersion := Scala212,
-  crossScalaVersions := Seq(Scala212, "2.13.14", "3.3.3"),
+  crossScalaVersions := Seq(Scala212, "2.13.15", "3.3.3"),
   scalacOptions ++= unusedWarnings.value,
   scalacOptions ++= {
     scalaBinaryVersion.value match {