rename identity challenge dir to challenge

Change-Id: Ieb89704404dae2086bd83987624670432bb69663
diff --git a/tests/unit-tests/requester.t.cpp b/tests/unit-tests/requester.t.cpp
index 4f2c8be..8fc2fe5 100644
--- a/tests/unit-tests/requester.t.cpp
+++ b/tests/unit-tests/requester.t.cpp
@@ -21,7 +21,7 @@
 #include "requester.hpp"
 #include "detail/error-encoder.hpp"
 #include "detail/probe-encoder.hpp"
-#include "identity-challenge/challenge-module.hpp"
+#include "challenge/challenge-module.hpp"
 #include "ca-module.hpp"
 #include "test-common.hpp"