chore(deps): update dependency org.apache.maven.plugins:maven-site-plugin to v3.21.0

Author: renovate[bot]

pom.xml

@@ -249,7 +249,7 @@
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-site-plugin</artifactId>
-          <version>3.20.0</version>
+          <version>3.21.0</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>