clang-diagnostic error: no member in the namespace 'std'

Clang was throwing no member named in 'std' error due to missing
inclusions.

Change-Id: I50d12ff604f2e9050b1d19891d3dbb80b878736f
Signed-off-by: Pavithra Barithaya <pavithrabarithaya07@gmail.com>
diff --git a/test/test_instance_id.hpp b/test/test_instance_id.hpp
index bbcd5f1..fee0000 100644
--- a/test/test_instance_id.hpp
+++ b/test/test_instance_id.hpp
@@ -2,6 +2,11 @@
 
 #include "common/instance_id.hpp"
 
+#include <string.h>
+#include <unistd.h>
+
+#include <filesystem>
+
 static constexpr uintmax_t pldmMaxInstanceIds = 32;
 
 class TestInstanceIdDb : public pldm::InstanceIdDb