Update dependency checkstyle to v10.21.1

build.gradle

@@ -91,7 +91,7 @@ allprojects {
 
   checkstyle {
     maxWarnings = 0
-    toolVersion = '10.18.2'
+    toolVersion = '10.21.1'
     // need to set configDir to rootDir otherwise submodule will use submodule/config/checkstyle
     getConfigDirectory().set(new File(rootDir, 'config/checkstyle'))
   }