Remove references to experimental filesystem

We're at CPP17 everywhere now, no need to keep the
experimental refrerence.

Change-Id: Ifd6af23c9bd8e40061b444436943c5192f9fc3e8
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/src/CPUSensorMain.cpp b/src/CPUSensorMain.cpp
index dcb8e24..a159714 100644
--- a/src/CPUSensorMain.cpp
+++ b/src/CPUSensorMain.cpp
@@ -14,8 +14,6 @@
 // limitations under the License.
 */
 
-#include "filesystem.hpp"
-
 #include <fcntl.h>
 
 #include <CPUSensor.hpp>
@@ -26,6 +24,7 @@
 #include <boost/container/flat_set.hpp>
 #include <boost/date_time/posix_time/posix_time.hpp>
 #include <boost/process/child.hpp>
+#include <filesystem>
 #include <fstream>
 #include <regex>
 #include <sdbusplus/asio/connection.hpp>