Update scala-library to 2.12.20

Author: typelevel-steward[bot]

build.sbt

@@ -17,7 +17,7 @@ ThisBuild / tlSonatypeUseLegacyHost := false
 ThisBuild / tlSitePublishBranch := Some("main")
 
 val Scala213 = "2.13.14"
-ThisBuild / crossScalaVersions := Seq("2.12.19", Scala213, "3.3.3")
+ThisBuild / crossScalaVersions := Seq("2.12.20", Scala213, "3.3.3")
 ThisBuild / scalaVersion := Scala213 // the default Scala
 
 lazy val root = tlCrossRootProject.aggregate(core)