Update dependency com.puppycrawl.tools:checkstyle to v10.21.1

Author: renovate[bot]

gradle/libs.versions.toml

@@ -5,7 +5,7 @@ asciidoctorj-pdf = "2.3.19"
 asciidoctor-plugins = "4.0.3" # Check if workaround in documentation.gradle.kts can be removed when upgrading
 assertj = "3.27.0"
 bnd = "7.1.0"
-checkstyle = "10.21.0"
+checkstyle = "10.21.1"
 eclipse = "4.34.0"
 jackson = "2.18.2"
 jacoco = "0.8.12"