Prevent forgetting to merge hotfix branches back into master

[grzesiek2010]

Problem description

We've recently run into an issue where changes made on a hotfix branch were not merged back into master after a point release was published (see #7271). This was not the first time this has happened, which suggests that relying on manual reminders and memory is not sufficient.

It would be good to discuss whether we should introduce a process improvement or automation to reduce the risk of this happening again.

Possible options

1. Automatically create a PR - Use CircleCI to automatically open/update a PR from the hotfix branch to master whenever changes are merged into the hotfix branch.
2. Add CI checks - Periodically check whether hotfix branches contain commits that are not present on master.
3. Add release checklist items - Include Merge hotfix branch changes back into master as part of the point release process.

The third option is the simplest one. We could add a step that, whenever a hotfix release is made, an issue is created to merge the changes back into master. This way, the person responsible doesn’t need to create a PR themselves.

[seadowg]

I'm wondering about just having an issue popped into the top of the backlog - I think that should be enough of a prompt? We could "script" that through @lognaturel's release checklist?