clean header file include

Change-Id: I5df52db13f964a92bba7cc8659ec6bcc222f5cbb
diff --git a/src/client-module.hpp b/src/client-module.hpp
index 47a5f63..c439d3c 100644
--- a/src/client-module.hpp
+++ b/src/client-module.hpp
@@ -22,7 +22,7 @@
 #define NDNCERT_CLIENT_MODULE_HPP
 
 #include "client-config.hpp"
-#include "certificate-request.hpp"
+#include "request-state.hpp"
 #include "crypto-support/crypto-helper.hpp"
 
 namespace ndn {