Update scala-library to 2.12.21

http4s-steward[bot] · http4s-steward[bot] · commit b37b3a42a703 · 2025-12-12T01:01:21.000Z
diff --git a/build.sbt b/build.sbt
@@ -31,7 +31,7 @@ ThisBuild / developers := List(
 )
 ThisBuild / startYear := Some(2021)
 
-ThisBuild / crossScalaVersions := Seq("3.3.6", "2.12.20", "2.13.16")
+ThisBuild / crossScalaVersions := Seq("3.3.6", "2.12.21", "2.13.16")
 
 ThisBuild / githubWorkflowBuildPreamble ++= Seq(
   WorkflowStep.Use(

Original file line number	Diff line number	Diff line change
`@@ -31,7 +31,7 @@ ThisBuild / developers := List(`
`31`	`31`	`)`
`32`	`32`	`ThisBuild / startYear := Some(2021)`
`33`	`33`
`34`		`-ThisBuild / crossScalaVersions := Seq("3.3.6", "2.12.20", "2.13.16")`
	`34`	`+ThisBuild / crossScalaVersions := Seq("3.3.6", "2.12.21", "2.13.16")`
`35`	`35`
`36`	`36`	`ThisBuild / githubWorkflowBuildPreamble ++= Seq(`
`37`	`37`	`WorkflowStep.Use(`