Slim down `ndncert-common.hpp`

Change-Id: Ifba0966d3787c5cbf770963b82cba054ee1fe791
diff --git a/src/redirection/redirection-param.cpp b/src/redirection/redirection-param.cpp
index 1ce9517..263d547 100644
--- a/src/redirection/redirection-param.cpp
+++ b/src/redirection/redirection-param.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2017-2022, Regents of the University of California.
+ * Copyright (c) 2017-2024, Regents of the University of California.
  *
  * This file is part of ndncert, a certificate management system based on NDN.
  *
@@ -20,7 +20,8 @@
 
 #include "redirection-param.hpp"
 
-#include <boost/algorithm/string.hpp>
+#include <boost/algorithm/string/classification.hpp>
+#include <boost/algorithm/string/split.hpp>
 
 namespace ndncert {
 
@@ -33,7 +34,7 @@
   }
 
   std::vector<std::string> strs;
-  boost::split(strs,format,boost::is_any_of("&"));
+  boost::split(strs, format, boost::is_any_of("&"));
   for (const auto& s : strs) {
     auto i = s.find('=');
     if (i == std::string::npos) {