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/TachSensor.hpp b/src/TachSensor.hpp
index 92c5202..b53b5ae 100644
--- a/src/TachSensor.hpp
+++ b/src/TachSensor.hpp
@@ -20,7 +20,7 @@
 {
   public:
     PresenceSensor(const std::string& gpioName, bool inverted,
-                   boost::asio::io_service& io, const std::string& name);
+                   boost::asio::io_context& io, const std::string& name);
     ~PresenceSensor();
 
     void monitorPresence(void);
@@ -70,7 +70,7 @@
                std::shared_ptr<sdbusplus::asio::connection>& conn,
                std::unique_ptr<PresenceSensor>&& presence,
                std::optional<RedundancySensor>* redundancy,
-               boost::asio::io_service& io, const std::string& fanName,
+               boost::asio::io_context& io, const std::string& fanName,
                std::vector<thresholds::Threshold>&& thresholds,
                const std::string& sensorConfiguration,
                const std::pair<double, double>& limits,