use filesystem instead of experimental

Use filesystem now that it should be available instead of
experimental::filesystem.

Change-Id: I62838b343ce34f85a47661f1eaaff3c7e6338bbf
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/sensor.cpp b/sensor.cpp
index 28f1479..d45f23a 100644
--- a/sensor.cpp
+++ b/sensor.cpp
@@ -10,7 +10,7 @@
 
 #include <cmath>
 #include <cstring>
-#include <experimental/filesystem>
+#include <filesystem>
 #include <phosphor-logging/elog-errors.hpp>
 #include <thread>
 #include <xyz/openbmc_project/Common/error.hpp>
@@ -189,7 +189,7 @@
 
 std::shared_ptr<StatusObject> Sensor::addStatus(ObjectInfo& info)
 {
-    namespace fs = std::experimental::filesystem;
+    namespace fs = std::filesystem;
 
     std::shared_ptr<StatusObject> iface = nullptr;
     auto& objPath = std::get<std::string>(info);