updated site parent

git-svn-id: https://svn.apache.org/repos/asf/maven/pom/trunk@1804252 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/maven/site-pom.xml b/maven/site-pom.xml
index 79777ab..22d7835 100644
--- a/maven/site-pom.xml
+++ b/maven/site-pom.xml
@@ -25,7 +25,7 @@
   <parent>
     <groupId>org.apache.maven</groupId>
     <artifactId>maven-parent</artifactId>
-    <version>30</version>
+    <version>31-SNAPSHOT</version>
     <relativePath>./pom.xml</relativePath>
   </parent>