[ci] test with dune 2.9
The release will only support dune 2.9 and not work with dune 2.8 anymore.
This also allows to simplify some Python stuff #1225 (closed)
The release will only support dune 2.9 and not work with dune 2.8 anymore.
This also allows to simplify some Python stuff #1225 (closed)
mentioned in merge request !3394 (merged)
mentioned in merge request !3399 (merged)
mentioned in commit d4a0bca7
closed with merge request !3399 (merged)