Update scala-library, scala-reflect to 2.12.20 (lightbend-labs#447)

Author: scala-steward

build.sbt

@@ -1,7 +1,7 @@
 // basics
 
 name := "scala-logging"
-crossScalaVersions := Seq("3.3.3", "2.11.12", "2.12.19", "2.13.14")
+crossScalaVersions := Seq("3.3.3", "2.11.12", "2.12.20", "2.13.14")
 scalaVersion := crossScalaVersions.value.head
 ThisBuild / versionScheme := Some("early-semver")
 scalacOptions ++= Seq(