Bump maven-site-plugin from 3.11.0 to 3.12.0

Bumps [maven-site-plugin](https://github.com/apache/maven-site-plugin) from 3.11.0 to 3.12.0.
- [Release notes](https://github.com/apache/maven-site-plugin/releases)
- [Commits](apache/maven-site-plugin@maven-site-plugin-3.11.0...maven-site-plugin-3.12.0)

---
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] <[email protected]>

pom.xml

@@ -64,7 +64,7 @@ under the License.
 
   <properties>
     <javaVersion>8</javaVersion>
-    <sitePluginVersion>3.11.0</sitePluginVersion>
+    <sitePluginVersion>3.12.0</sitePluginVersion>
     <javadocPluginVersion>3.4.0</javadocPluginVersion>
     <maven.site.path>jxr-archives/jxr-LATEST</maven.site.path>
     <checkstyle.violation.ignore>None</checkstyle.violation.ignore>