sdbusplus: replace message::variant with std::variant

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib9964827982a5a495204bc3230caa22039f6145e
diff --git a/activation.cpp b/activation.cpp
index cd4b367..382eae0 100644
--- a/activation.cpp
+++ b/activation.cpp
@@ -384,7 +384,7 @@
         {
             auto reply = bus.call(method);
 
-            sdbusplus::message::variant<std::string> result;
+            std::variant<std::string> result;
             reply.read(result);
             auto applyTime = std::get<std::string>(result);
             if (applyTime == applyTimeImmediate)