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/FanMain.cpp b/src/FanMain.cpp
index 2c51396..2756213 100644
--- a/src/FanMain.cpp
+++ b/src/FanMain.cpp
@@ -227,7 +227,7 @@
 }
 
 void createSensors(
-    boost::asio::io_service& io, sdbusplus::asio::object_server& objectServer,
+    boost::asio::io_context& io, sdbusplus::asio::object_server& objectServer,
     boost::container::flat_map<std::string, std::shared_ptr<TachSensor>>&
         tachSensors,
     boost::container::flat_map<std::string, std::unique_ptr<PwmSensor>>&
@@ -541,7 +541,7 @@
 
 int main()
 {
-    boost::asio::io_service io;
+    boost::asio::io_context io;
     auto systemBus = std::make_shared<sdbusplus::asio::connection>(io);
     sdbusplus::asio::object_server objectServer(systemBus, true);