Include what you use

Do a partial update from the include what you use tool.

While ideally we'd be able to do this as part of CI, there's still quite
a bit of noise in the output that requires manual intervention.

Tested:
Code compiles

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Iaaeb7a9199f64b5d6913c3abab4779b252768ed8
diff --git a/http/utility.hpp b/http/utility.hpp
index 74a35da..41182e4 100644
--- a/http/utility.hpp
+++ b/http/utility.hpp
@@ -1,18 +1,21 @@
 #pragma once
-#include "nlohmann/json.hpp"
 
 #include <openssl/crypto.h>
 
 #include <boost/date_time/posix_time/posix_time.hpp>
 
+#include <array>
 #include <chrono>
 #include <cstdint>
-#include <cstring>
+#include <ctime>
 #include <functional>
-#include <regex>
+#include <limits>
 #include <stdexcept>
 #include <string>
+#include <string_view>
 #include <tuple>
+#include <type_traits>
+#include <utility>
 
 namespace crow
 {