Boost.System no longer has a library.

--- 6782a1f934bc6c3bd293d34ab7453a85b00f4fab/CMakeLists.txt	2025-04-25 13:55:18.000000000 +0100
+++ 6782a1f934bc6c3bd293d34ab7453a85b00f4fab/CMakeLists.txt	2025-08-15 06:11:15.282391961 +0100
@@ -71,7 +71,7 @@
 ########################################################################
 # Find boost
 ########################################################################
-find_package(Boost "1.65" REQUIRED system)
+find_package(Boost "1.65" REQUIRED)
 
 if(NOT Boost_FOUND)
     message(FATAL_ERROR "Boost required to compile iqbalance")