PHOENIX-7613 Update Apache parent pom to 31 (#180)

diff --git a/pom.xml b/pom.xml
index c3fe064..72e4dca 100644
--- a/pom.xml
+++ b/pom.xml
@@ -26,7 +26,7 @@
     <parent>
       <groupId>org.apache</groupId>
       <artifactId>apache</artifactId>
-      <version>30</version>
+      <version>31</version>
     </parent>
 
     <groupId>org.apache.phoenix</groupId>