Bump com.puppycrawl.tools:checkstyle from 10.20.2 to 10.21.1

Bumps [com.puppycrawl.tools:checkstyle](https://github.com/checkstyle/checkstyle) from 10.20.2 to 10.21.1.
- [Release notes](https://github.com/checkstyle/checkstyle/releases)
- [Commits](checkstyle/checkstyle@checkstyle-10.20.2...checkstyle-10.21.1)

---
updated-dependencies:
- dependency-name: com.puppycrawl.tools:checkstyle
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -39,7 +39,7 @@
     <maven-shade-plugin.version>3.6.0</maven-shade-plugin.version>
     <editorconfig-maven-plugin.version>0.1.3</editorconfig-maven-plugin.version> <!-- XXX: Remove linter dependency overrides when upgrading from 0.1.3 -->
     <maven-checkstyle-plugin.version>3.6.0</maven-checkstyle-plugin.version>
-    <maven-checkstyle-plugin.checkstyle.version>10.20.2</maven-checkstyle-plugin.checkstyle.version>
+    <maven-checkstyle-plugin.checkstyle.version>10.21.1</maven-checkstyle-plugin.checkstyle.version>
     <maven-pmd-plugin.version>3.26.0</maven-pmd-plugin.version>
     <maven-pmd-plugin.pmd-core.version>7.8.0</maven-pmd-plugin.pmd-core.version>
     <maven-pmd-plugin.pmd-java.version>7.8.0</maven-pmd-plugin.pmd-java.version>