gnucash stable: Bump minimum cmake version to 3.16

[Geert Janssens]

Updated	 via  https://github.com/Gnucash/gnucash/commit/6c99523a (commit)
	from  https://github.com/Gnucash/gnucash/commit/51e932c9 (commit)



commit 6c99523a70068653b9c73fd3946794987e011b6e
Author: Geert Janssens <geert at kobaltwit.be>
Date:   Fri Aug 18 18:46:38 2023 +0200

    Bump minimum cmake version to 3.16
    
    This allows to drop some conditionals for older versions



Summary of changes:
 CMakeLists.txt | 26 ++++----------------------
 1 file changed, 4 insertions(+), 22 deletions(-)