Bump org.apache.maven.plugins:maven-site-plugin from 3.12.1 to 3.20.0

Bumps [org.apache.maven.plugins:maven-site-plugin](https://github.com/apache/maven-site-plugin) from 3.12.1 to 3.20.0.
- [Commits](apache/maven-site-plugin@maven-site-plugin-3.12.1...maven-site-plugin-3.20.0)

---
updated-dependencies:
- dependency-name: org.apache.maven.plugins:maven-site-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -131,7 +131,7 @@ under the License.
     <version.maven-scm-plugin>2.1.0</version.maven-scm-plugin>
     <version.maven-scm-publish-plugin>3.3.0</version.maven-scm-publish-plugin>
     <version.maven-shade-plugin>3.6.0</version.maven-shade-plugin>
-    <version.maven-site-plugin>3.12.1</version.maven-site-plugin>
+    <version.maven-site-plugin>3.20.0</version.maven-site-plugin>
     <version.maven-source-plugin>3.3.1</version.maven-source-plugin>
     <version.maven-surefire>${surefire.version}</version.maven-surefire>
     <version.maven-war-plugin>3.4.0</version.maven-war-plugin>