chore(deps): update dependency org.apache.maven.plugins:maven-site-plugin to v3.20.0 (#1473)

Author: renovate-bot

google-auth-library-java/bom/pom.xml

@@ -91,7 +91,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-site-plugin</artifactId>
-        <version>3.12.1</version>
+        <version>3.20.0</version>
         <configuration>
           <skip>true</skip>
         </configuration>

google-auth-library-java/pom.xml

@@ -280,7 +280,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-site-plugin</artifactId>
-        <version>3.12.1</version>
+        <version>3.20.0</version>
         <configuration>
           <skipDeploy>true</skipDeploy>
         </configuration>