Update scala-compiler, scala-library to 2.12.21

Author: scala-steward

.circleci/config.yml

@@ -98,7 +98,7 @@ workflows:
       - scala_job:
           name: 2.12.x
           java_version: jdk8
-          scala_version: 2.12.20
+          scala_version: 2.12.21
       - scala_job:
           name: 2.13.x
           java_version: jdk8
@@ -110,7 +110,7 @@ workflows:
       - scala_job:
           name: jdk11_2.12.x
           java_version: jdk11
-          scala_version: 2.12.20
+          scala_version: 2.12.21
       - scala_job:
           name: jdk11_2.13.x
           java_version: jdk11
@@ -122,7 +122,7 @@ workflows:
       - scala_job:
           name: jdk17_2.12.x
           java_version: jdk17
-          scala_version: 2.12.20
+          scala_version: 2.12.21
       - scala_job:
           name: jdk17_2.13.x
           java_version: jdk17
@@ -134,7 +134,7 @@ workflows:
       - scala_job:
           name: jdk21_2.12.x
           java_version: jdk21
-          scala_version: 2.12.20
+          scala_version: 2.12.21
       - scala_job:
           name: jdk21_2.13.x
           java_version: jdk21
@@ -145,7 +145,7 @@ workflows:
           scala_version: 3.3.7
       - scalajs_job:
           name: sjs1.0_2.12.x
-          scala_version: 2.12.20
+          scala_version: 2.12.21
       - scalajs_job:
           name: sjs1.0_2.13.x
           scala_version: 2.13.18
@@ -154,7 +154,7 @@ workflows:
           scala_version: 3.3.7
       - scalanative_job:
           name: native0.4_2.12.x
-          scala_version: 2.12.20
+          scala_version: 2.12.21
       - scalanative_job:
           name: native0.4_2.13.x
           scala_version: 2.13.18

build.sbt

@@ -37,8 +37,8 @@ lazy val xml = crossProject(JSPlatform, JVMPlatform, NativePlatform)
   .settings(
     name    := "scala-xml",
     scalaModuleAutomaticModuleName := Some("scala.xml"),
-    crossScalaVersions := Seq("2.13.18", "2.12.20", "3.3.7"),
-    scalaVersion := "2.12.20",
+    crossScalaVersions := Seq("2.13.18", "2.12.21", "3.3.7"),
+    scalaVersion := "2.12.21",
 
     scalacOptions ++= (CrossVersion.partialVersion(scalaVersion.value) match {
       case Some((3, _)) =>