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

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I7b2bc0a8b34e4d276c0e8ea2243459aab4e1c177
diff --git a/monitor/tach_sensor.cpp b/monitor/tach_sensor.cpp
index e366872..2bf7b06 100644
--- a/monitor/tach_sensor.cpp
+++ b/monitor/tach_sensor.cpp
@@ -181,7 +181,7 @@
                                     T& value)
 {
     std::string sensor;
-    std::map<std::string, sdbusplus::message::variant<T>> data;
+    std::map<std::string, std::variant<T>> data;
     msg.read(sensor, data);
 
     if (sensor.compare(interface) == 0)