Replace std::experimental::filesystem with std::filesystem

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I91d2f1b7a8858ba8c676b68693863bb35b56dffc
diff --git a/test/error_files_tests.cpp b/test/error_files_tests.cpp
index c412e63..6931cdc 100644
--- a/test/error_files_tests.cpp
+++ b/test/error_files_tests.cpp
@@ -17,7 +17,7 @@
 constexpr auto legacyErrorTemp = "occ_dvfs_ot";
 constexpr auto noError = "0";
 
-namespace fs = std::experimental::filesystem;
+namespace fs = std::filesystem;
 using namespace open_power::occ;
 
 class ErrorFiles : public ::testing::Test