Update logback-classic to 1.5.21 (#378)

Author: softwaremill-ci

build.sbt

@@ -39,7 +39,7 @@ val enableMimaSettings = Seq(
 
 val scalaTest = "org.scalatest" %% "scalatest" % "3.2.19" % Test
 val slf4j = "org.slf4j" % "slf4j-api" % "2.0.17"
-val logback = "ch.qos.logback" % "logback-classic" % "1.5.20"
+val logback = "ch.qos.logback" % "logback-classic" % "1.5.21"
 
 // used during CI to verify that the documentation compiles
 val compileDocumentation: TaskKey[Unit] = taskKey[Unit]("Compiles documentation throwing away its output")