Update logback-classic to 1.5.21 (#162)

Co-authored-by: horothesun-scala-steward[bot] <132169906+horothesun-scala-steward[bot]@users.noreply.github.com>

Author: horothesun-scala-steward[bot]

project/Dependencies.scala

@@ -15,7 +15,7 @@ object Dependencies {
 
     val awsLambdaEvents = "3.16.1"
 
-    val logbackClassic = "1.5.20"
+    val logbackClassic = "1.5.21"
 
     val munitScalaCheck = "1.2.0"