MLECO-4072: update MLEK dependencies to 23.08

* version updates in cmakelists file
* update submodules to 23.08 versions
* updates to documentation - vela 3.9.0

Change-Id: I5e24d5729ecbd2289b04fcc845fb44f455ab38d5
Signed-off-by: Nina Drozd <nina.drozd@arm.com>