Bump checkstyle to 10.21.1

https://checkstyle.org/releasenotes.html#Release_10.21.0
https://checkstyle.org/releasenotes.html#Release_10.21.1

Change-Id: I67da9b1e4c2ba7e0200d02e8990e84fe65932a0a
Signed-off-by: Robert Varga <[email protected]>

Author: rovarga

odlparent/pom.xml

@@ -126,7 +126,7 @@
         <groupId>com.puppycrawl.tools</groupId>
         <artifactId>checkstyle</artifactId>
         <!-- This should match the plugin management on maven-checkstyle-plugin below -->
-        <version>10.20.1</version>
+        <version>10.21.1</version>
       </dependency>
 
       <!-- Testing Dependencies -->
@@ -868,7 +868,7 @@
               <groupId>com.puppycrawl.tools</groupId>
               <artifactId>checkstyle</artifactId>
               <!-- This should match the dependency management on com.puppycrawl.tools:checkstyle above -->
-              <version>10.20.1</version>
+              <version>10.21.1</version>
             </dependency>
             <dependency>
               <groupId>org.opendaylight.odlparent</groupId>