Autorebase WIP branches when there's a change in the stable branch

For example, when `4.1` has a new commit, `wip/4.1` should be rebased on top of it.

Same for:
* `main` and `wip/4.2`
* `4.1` and `wip/4.1`
* `3.2` and `wip/3.2`
* `3.1` and `wip/3.1`
* `2.4` and `wip/2.4`