Update scala-library, scala-reflect to 2.13.8

Author: scala-steward

build.sbt

@@ -5,7 +5,7 @@ import com.softwaremill.SbtSoftwareMillCommon.commonSmlBuildSettings
 import com.softwaremill.Publish.{ossPublishSettings, updateDocs}
 
 val scala212 = "2.12.15"
-val scala213 = "2.13.6"
+val scala213 = "2.13.8"
 val scala3 = "3.1.0"
 
 val scalaIdeaVersion = scala3 // the version for which to import sources into intellij