Fix sdbusplus::server::object template wrapper

The aliased template is vararg, so make the alias vararg as well.

Change-Id: Ib562c09f625439c4b5f1234047dfc9378043cfb9
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/interface.hpp b/interface.hpp
index 911aa14..4196098 100644
--- a/interface.hpp
+++ b/interface.hpp
@@ -5,8 +5,8 @@
 #include <xyz/openbmc_project/Sensor/Threshold/Critical/server.hpp>
 #include <sdbusplus/server.hpp>
 
-template <typename T>
-using ServerObject = typename sdbusplus::server::object::object<T>;
+template <typename... T>
+using ServerObject = typename sdbusplus::server::object::object<T...>;
 
 using ValueInterface = sdbusplus::xyz::openbmc_project::Sensor::server::Value;
 using ValueObject = ServerObject<ValueInterface>;