chore(cubicweb): stop to claim that we support old versions
It may still work with old versions, but we have to get rid of them and the old versions are still available if needed.
- CubicWeb 4.5.2 was published at the end of 2023. We would have liked to upgrade more, however CubicWeb 4.5.2 is still used by at least one active project and it would benefit from a merge request for next version (!51 (merged)).
- It is unlikely that CubicWeb-Web 1.3.3 or above introduce regression(s), but it is certain to remove some problems.