Update to newer maven-site-plugin.


git-svn-id: https://svn.apache.org/repos/asf/creadur/tentacles/trunk@1820782 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index e905883..5cf6f96 100644
--- a/pom.xml
+++ b/pom.xml
@@ -197,6 +197,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-site-plugin</artifactId>
+        <version>3.7</version>
         <configuration>
           <outputEncoding>${project.build.sourceEncoding}</outputEncoding>
           <inputEncoding>${project.build.sourceEncoding}</inputEncoding>