Remove boost_system component from find_package

Boost 1.89.0 removed the separate boost_system compiled library.
The boost::system headers are still available through the core Boost package.
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -79,7 +79,7 @@ endif ()


 find_package (Boost 1.38 REQUIRED
-    COMPONENTS filesystem iostreams program_options regex system)
+    COMPONENTS filesystem iostreams program_options regex)

 include(FetchContent)
 FetchContent_Declare(