Update checkstyle dependency to fix security vulnerability (#11497)

pom.xml

@@ -475,12 +475,10 @@
                     <artifactId>maven-checkstyle-plugin</artifactId>
                     <version>2.17</version>
                     <dependencies>
-                        <!-- Needed because of a JavadocMethodCheck bug in 
-                            6.11 -->
                         <dependency>
                             <groupId>com.puppycrawl.tools</groupId>
                             <artifactId>checkstyle</artifactId>
-                            <version>6.17</version>
+                            <version>8.18</version>
                         </dependency>
                     </dependencies>
                     <configuration>