clean header file include

Change-Id: I5df52db13f964a92bba7cc8659ec6bcc222f5cbb
diff --git a/src/challenge-module/challenge-pin.hpp b/src/challenge-module/challenge-pin.hpp
index 9e7d8b0..0b73cb2 100644
--- a/src/challenge-module/challenge-pin.hpp
+++ b/src/challenge-module/challenge-pin.hpp
@@ -22,7 +22,6 @@
 #define NDNCERT_CHALLENGE_PIN_HPP
 
 #include "../challenge-module.hpp"
-#include <ndn-cxx/util/time.hpp>
 
 namespace ndn {
 namespace ndncert {
@@ -53,7 +52,7 @@
 
   // For CA
   std::tuple<ErrorCode, std::string>
-  handleChallengeRequest(const Block& params, CertificateRequest& request) override;
+  handleChallengeRequest(const Block& params, RequestState& request) override;
 
   // For Client
   std::vector<std::tuple<std::string, std::string>>