Remove extra call to execute

Author: jeffgabhart

src/ServiceStack.OrmLite.PostgreSQL/PostgreSQLDialectProvider.cs

@@ -387,8 +387,6 @@ public override void PrepareStoredProcedureStatement<T>(IDbCommand cmd, T obj)
             }
 
             SetParameterValues<T>(cmd, obj);
-
-            cmd.ExecuteNonQuery();
         }
     }
 }