Upgrade to commons-parent version 15

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/compress/trunk@936207 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 6eca881..2648c3a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.commons</groupId>
     <artifactId>commons-parent</artifactId>
-    <version>14</version>
+    <version>15</version>
   </parent>
 
   <artifactId>commons-compress</artifactId>