[2pt] Add signed-off-by in commit messages

[codificat]

Problem statement

When Kebechet sends e.g. a PR to update dependencies, the commit message(s) do not contain a Signed-off-by: line.

This can prevent DCO checks from working.

Example: https://github.com/os-climate/data-platform-demo/pull/41/checks?check_run_id=6642425305

High-level Goals

To have all of Kebechet's commits Signed-off-by the bot.

Acceptance Criteria

• [ ] for every commit that Kebechet generates, the commit message always includes a line Signed-off-by: Kebechet <kebechet-s@email.example.com>

[codificat]

/sig user-experience /priority important-soon /kind feature

[Gkrumbach07]

story points 2

[codificat]

/wg cnbi