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

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I20d317adc625900076b1025d8645fd4dd22334e7
diff --git a/include/pulse_event_monitor.hpp b/include/pulse_event_monitor.hpp
index 4402453..15d2531 100644
--- a/include/pulse_event_monitor.hpp
+++ b/include/pulse_event_monitor.hpp
@@ -24,8 +24,7 @@
 {
     auto pulseEventMatcherCallback = [](sdbusplus::message::message &msg) {
         std::string thresholdInterface;
-        boost::container::flat_map<std::string,
-                                   sdbusplus::message::variant<std::string>>
+        boost::container::flat_map<std::string, std::variant<std::string>>
             propertiesChanged;
         msg.read(thresholdInterface, propertiesChanged);