lock shade plugin version

git-svn-id: https://svn.apache.org/repos/asf/maven/ant-tasks/trunk@1411018 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 73a4c19..3c65286 100644
--- a/pom.xml
+++ b/pom.xml
@@ -238,6 +238,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-shade-plugin</artifactId>
+        <version>1.7</version>
         <executions>
           <execution>
             <phase>package</phase>