Update scala-library, scala-reflect to 2.12.19

Author: typelevel-steward[bot]

build.sbt

@@ -14,7 +14,7 @@ val GraalVM = JavaSpec.graalvm("17")
 
 ThisBuild / githubWorkflowJavaVersions := Seq(PrimaryJava, LTSJava, GraalVM)
 
-val Scala212 = "2.12.18"
+val Scala212 = "2.12.19"
 val Scala213 = "2.13.13"
 val Scala3 = "3.3.1"