Change io_service to io_context

This was renamed a while back in boost to be compliant with the
std::executors proposal.

Change-Id: Ib56544a0a7478990d18fe9e0bbbd8db1e52fa5b8
Signed-off-by: Ed Tanous <edtanous@google.com>
diff --git a/src/NVMeContext.hpp b/src/NVMeContext.hpp
index bcfa5d6..14e38a1 100644
--- a/src/NVMeContext.hpp
+++ b/src/NVMeContext.hpp
@@ -2,7 +2,7 @@
 
 #include "NVMeSensor.hpp"
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/steady_timer.hpp>
 
 #include <memory>
@@ -11,7 +11,7 @@
 class NVMeContext : public std::enable_shared_from_this<NVMeContext>
 {
   public:
-    NVMeContext(boost::asio::io_service& io, int rootBus) :
+    NVMeContext(boost::asio::io_context& io, int rootBus) :
         scanTimer(io), rootBus(rootBus), pollCursor(sensors.end())
     {
         if (rootBus < 0)