Update scala-library, scala-reflect to 2.13.15

Author: scala-steward

build.sbt

@@ -4,7 +4,7 @@ import com.softwaremill.UpdateVersionInDocs
 
 val scala211 = "2.11.12"
 val scala212 = "2.12.19"
-val scala213 = "2.13.14"
+val scala213 = "2.13.15"
 val scala3 = "3.3.3"
 
 val scalaIdeaVersion = scala3 // the version for which to import sources into intellij