Consistently reuse project version number in pom

Change-Id: I4f5dca5b20e7b5c8ead6ca3cd6c5873af238515a
diff --git a/pom.xml b/pom.xml
index 41cf343..dc48bcf 100644
--- a/pom.xml
+++ b/pom.xml
@@ -27,7 +27,7 @@
 
   <properties>
     <Gerrit-ApiType>plugin</Gerrit-ApiType>
-    <Gerrit-ApiVersion>2.16</Gerrit-ApiVersion>
+    <Gerrit-ApiVersion>${project.version}</Gerrit-ApiVersion>
   </properties>
 
   <build>