bmcweb: move variant usage to std namespace

Change-Id: I9d7069668f91f2ac72d2f4a440f63e0e85dd5269
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/include/image_upload.hpp b/include/image_upload.hpp
index 6b87530..6bf5661 100644
--- a/include/image_upload.hpp
+++ b/include/image_upload.hpp
@@ -66,8 +66,7 @@
             sdbusplus::message::object_path path;
             std::vector<std::pair<
                 std::string,
-                std::vector<std::pair<
-                    std::string, sdbusplus::message::variant<std::string>>>>>
+                std::vector<std::pair<std::string, std::variant<std::string>>>>>
                 interfaces;
             m.read(path, interfaces);