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>
diff --git a/set_up_default_resources.py b/set_up_default_resources.py
index b442432..f983508 100755
--- a/set_up_default_resources.py
+++ b/set_up_default_resources.py
@@ -382,7 +382,7 @@
     metadata_file_path = download_dir / "resources_downloaded_metadata.json"
 
     metadata_dict = dict()
-    vela_version = "3.8.0"
+    vela_version = "3.9.0"
     py3_version_minimum = (3, 9)
 
     # Is Python minimum requirement matched?