Conditionaly include postgresql::server::contrib

We need the contrib packages only with older versions of PostgreSQL.
While here include this class when it is needed instead of using
a resource to avoid conflicts when another module wants to do this.

Author: smortex

manifests/database/postgresql.pp

@@ -60,7 +60,9 @@
     if $manage_database {
 
       # get the pg contrib to use pg_trgm extension
-      class { '::postgresql::server::contrib': }
+      if (versioncmp($postgres_version, '10') < 0) {
+        include postgresql::server::contrib
+      }
 
       postgresql::server::extension { 'pg_trgm':
         database => $database_name,