Change io_service to io_context

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

Change-Id: I67eb15038f2aa6957738fa5e3f6c14fd66460b7a
Signed-off-by: Ed Tanous <edtanous@google.com>
diff --git a/attn/attn_main.cpp b/attn/attn_main.cpp
index 0c3f250..84c3bba 100644
--- a/attn/attn_main.cpp
+++ b/attn/attn_main.cpp
@@ -12,7 +12,7 @@
 
     gpiod_line* line; // gpio line to monitor
 
-    boost::asio::io_service io; // async io monitoring service
+    boost::asio::io_context io; // async io monitoring service
 
     // GPIO line configuration (falling edge, active low)
     struct gpiod_line_request_config config
diff --git a/attn/attn_monitor.hpp b/attn/attn_monitor.hpp
index ac791cd..9680fda 100644
--- a/attn/attn_monitor.hpp
+++ b/attn/attn_monitor.hpp
@@ -3,7 +3,7 @@
 #include <gpiod.h>
 
 #include <attn/attn_config.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/posix/stream_descriptor.hpp>
 
 namespace attn
@@ -29,7 +29,7 @@
      * @param i_attnConfig poiner to attention handler configuration object
      */
     AttnMonitor(gpiod_line* line, gpiod_line_request_config& config,
-                boost::asio::io_service& io, Config* i_attnConfig) :
+                boost::asio::io_context& io, Config* i_attnConfig) :
         iv_gpioLine(line),
         iv_gpioConfig(config), iv_gpioEventDescriptor(io),
         iv_config(i_attnConfig)