Update dependency org.apache.maven.plugins:maven-site-plugin to v3.20.0

Author: renovate[bot]

pom.xml

@@ -210,7 +210,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-site-plugin</artifactId>
-                <version>3.12.1</version>
+                <version>3.20.0</version>
                 <configuration>
                     <relativizeDecorationLinks>false</relativizeDecorationLinks>
                 </configuration>