FindBoost: Prevent warning with boost 1.73

In commit 9daf79c5 (FindBoost: Add support for Boost 1.73, 2020-04-19)
we forgot to update the version comparison for the warning.

This amends commit 9daf79c5

Modules/FindBoost.cmake

@@ -1179,7 +1179,7 @@ function(_Boost_COMPONENT_DEPENDENCIES component _ret)
       set(_Boost_TIMER_DEPENDENCIES chrono)
       set(_Boost_WAVE_DEPENDENCIES filesystem serialization thread chrono date_time atomic)
       set(_Boost_WSERIALIZATION_DEPENDENCIES serialization)
-      if(NOT Boost_VERSION_STRING VERSION_LESS 1.73.0)
+      if(Boost_VERSION_STRING VERSION_GREATER_EQUAL 1.74.0)
         message(WARNING "New Boost version may have incorrect or missing dependencies and imported targets")
       endif()
     endif()