gnucash stable: Don't try to find boost::system in boost 1.89.0 and later

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/7e53cbad (commit)
	from  https://github.com/Gnucash/gnucash/commit/00149932 (commit)



commit 7e53cbad4d9b6b68a69d7b4fabc33849dd77c9d0
Author: John Ralls <jralls at ceridwen.us>
Date:   Thu Oct 23 13:48:51 2025 -0700

    Don't try to find boost::system in boost 1.89.0 and later
    
    They made it header-only so there's nothing to find.



Summary of changes:
 CMakeLists.txt                            | 10 +++++++++-
 util/ci/actions/archlinux-test/Dockerfile |  2 +-
 2 files changed, 10 insertions(+), 2 deletions(-)