CI: bump to Octave 6.4.0

(manually cherry picked from commit 1280566b)

.gitlab-ci.yml

@@ -3,7 +3,7 @@ variables:
   TERM: linux
   MATLAB_VERSION: R2021b
   OLD_MATLAB_VERSION: R2014a
-  OCTAVE_VERSION: 6.3.0
+  OCTAVE_VERSION: 6.4.0
 
 # The next stanza creates the version number used for the source tarball and the
 # binary packages. Here are the following possible cases:

dseries @ 2adbe30e

-Subproject commit d443d9573ab6e6be1628b839f4fb041ca70538ff
+Subproject commit 2adbe30e207e5fbb43d401579b32a11a5984a89f

reporting @ 54e6db2a

-Subproject commit 0a9a93dd1c79b00b067ccea5b8afc4ec93c32fd7
+Subproject commit 54e6db2a5c330b1576245b909396a328915ae6d2