deal with Boost 1.89 not having system as component anymore.

CMakeLists.txt

@@ -92,11 +92,19 @@ endif ()
 set(ROOT_GRTEQ_24 ${ROOT_GRTEQ_24} CACHE INTERNAL "ROOT Version check")
 
 #--- check for boost ----------------------------------------------------------
-find_package(Boost REQUIRED
-  COMPONENTS
-    system
-    filesystem
-)
+find_package(Boost QUIET)
+if (Boost_VERSION VERSION_GREATER_EQUAL "1.89")
+  find_package(Boost REQUIRED
+    COMPONENTS
+      filesystem
+  )
+else (Boost_VERSION VERSION_GREATER_EQUAL "1.89")
+  find_package(Boost REQUIRED
+    COMPONENTS
+      system
+      filesystem
+  )
+endif (Boost_VERSION VERSION_GREATER_EQUAL "1.89")
 message(STATUS "Boost libs: ${Boost_LIBRARIES}")
 
 #--- check for gsl ------------------------------------------------------------