Bump com.puppycrawl.tools:checkstyle from 10.20.2 to 10.21.0

Bumps [com.puppycrawl.tools:checkstyle](https://github.com/checkstyle/checkstyle) from 10.20.2 to 10.21.0.
- [Release notes](https://github.com/checkstyle/checkstyle/releases)
- [Commits](checkstyle/checkstyle@checkstyle-10.20.2...checkstyle-10.21.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -99,7 +99,7 @@
     <maven-pmd-plugin.version>3.26.0</maven-pmd-plugin.version>
     <pmd.version>7.7.0</pmd.version>
     <maven-checkstyle-plugin.version>3.6.0</maven-checkstyle-plugin.version>
-    <checkstyle.version>10.20.2</checkstyle.version>
+    <checkstyle.version>10.21.0</checkstyle.version>
     <spotbugs-maven-plugin.version>4.8.6.6</spotbugs-maven-plugin.version>
     <findsecbugs-plugin.version>1.13.0</findsecbugs-plugin.version>
     <jacoco-maven-plugin.version>0.8.12</jacoco-maven-plugin.version>